diff --git a/testing/web-platform/tests/navigation-api/currententrychange-event/navigation-navigate-transitionWhile.html b/testing/web-platform/tests/navigation-api/currententrychange-event/navigation-navigate-intercept.html
similarity index 88%
rename from testing/web-platform/tests/navigation-api/currententrychange-event/navigation-navigate-transitionWhile.html
rename to testing/web-platform/tests/navigation-api/currententrychange-event/navigation-navigate-intercept.html
index e5855cf63e815..af0fe104f944f 100644
--- a/testing/web-platform/tests/navigation-api/currententrychange-event/navigation-navigate-transitionWhile.html
+++ b/testing/web-platform/tests/navigation-api/currententrychange-event/navigation-navigate-intercept.html
@@ -13,9 +13,9 @@
     assert_equals(e.navigationType, "push");
     assert_equals(i.contentWindow.navigation.currentEntry.index, 1);
   });
-  i.contentWindow.navigation.onnavigate = e => e.transitionWhile(Promise.resolve());
+  i.contentWindow.navigation.onnavigate = e => e.intercept();
   let result = i.contentWindow.navigation.navigate("/common/blank.html?1");
   assert_true(oncurrententrychange_called);
   await result.committed;
-}, "currententrychange fires for navigation.navigate() intercepted by transitionWhile()");
+}, "currententrychange fires for navigation.navigate() intercepted by intercept()");
 </script>
diff --git a/testing/web-platform/tests/navigation-api/currententrychange-event/navigation-navigate-replace-transitionWhile.html b/testing/web-platform/tests/navigation-api/currententrychange-event/navigation-navigate-replace-intercept.html
similarity index 88%
rename from testing/web-platform/tests/navigation-api/currententrychange-event/navigation-navigate-replace-transitionWhile.html
rename to testing/web-platform/tests/navigation-api/currententrychange-event/navigation-navigate-replace-intercept.html
index 9e1401233b21a..33209202d8ce0 100644
--- a/testing/web-platform/tests/navigation-api/currententrychange-event/navigation-navigate-replace-transitionWhile.html
+++ b/testing/web-platform/tests/navigation-api/currententrychange-event/navigation-navigate-replace-intercept.html
@@ -15,9 +15,9 @@
     assert_equals(e.navigationType, "replace");
     assert_equals(i.contentWindow.navigation.currentEntry.index, 0);
   });
-  i.contentWindow.navigation.onnavigate = e => e.transitionWhile(Promise.resolve());
+  i.contentWindow.navigation.onnavigate = e => e.intercept();
   let result = i.contentWindow.navigation.navigate("/common/blank.html?1", { history: "replace" });
   assert_true(oncurrententrychange_called);
   await result.committed;
-}, "currententrychange fires for navigation.navigate() with replace intercepted by transitionWhile()");
+}, "currententrychange fires for navigation.navigate() with replace intercepted by intercept()");
 </script>
diff --git a/testing/web-platform/tests/navigation-api/currententrychange-event/navigation-reload-transitionWhile.html b/testing/web-platform/tests/navigation-api/currententrychange-event/navigation-reload-intercept.html
similarity index 87%
rename from testing/web-platform/tests/navigation-api/currententrychange-event/navigation-reload-transitionWhile.html
rename to testing/web-platform/tests/navigation-api/currententrychange-event/navigation-reload-intercept.html
index c732de941f7ed..275e23363c9bf 100644
--- a/testing/web-platform/tests/navigation-api/currententrychange-event/navigation-reload-transitionWhile.html
+++ b/testing/web-platform/tests/navigation-api/currententrychange-event/navigation-reload-intercept.html
@@ -13,9 +13,9 @@
     assert_equals(e.navigationType, "reload");
     assert_equals(i.contentWindow.navigation.currentEntry.index, 0);
   });
-  i.contentWindow.navigation.onnavigate = e => e.transitionWhile(Promise.resolve());
+  i.contentWindow.navigation.onnavigate = e => e.intercept();
   let result = i.contentWindow.navigation.reload();
   assert_true(oncurrententrychange_called);
   await result.committed;
-}, "currententrychange fires for navigation.reload() intercepted by transitionWhile()");
+}, "currententrychange fires for navigation.reload() intercepted by intercept()");
 </script>
diff --git a/testing/web-platform/tests/navigation-api/focus-reset/autofocus.html b/testing/web-platform/tests/navigation-api/focus-reset/autofocus.html
index 4418dfa76cde7..60444473673bb 100644
--- a/testing/web-platform/tests/navigation-api/focus-reset/autofocus.html
+++ b/testing/web-platform/tests/navigation-api/focus-reset/autofocus.html
@@ -23,7 +23,7 @@
   assert_equals(document.activeElement, decoy, "focus() worked");
 
   navigation.addEventListener("navigate", e => {
-    e.transitionWhile(Promise.resolve());
+    e.intercept();
   }, { once: true });
 
   const { committed, finished } = navigation.navigate("#1");
@@ -44,7 +44,7 @@
   assert_equals(document.activeElement, decoy, "focus() worked");
 
   navigation.addEventListener("navigate", e => {
-    e.transitionWhile(Promise.resolve());
+    e.intercept();
   }, { once: true });
 
   const { committed, finished } = navigation.navigate("#1");
@@ -65,7 +65,7 @@
   assert_equals(document.activeElement, decoy, "focus() worked");
 
   navigation.addEventListener("navigate", e => {
-    e.transitionWhile(Promise.resolve());
+    e.intercept();
   }, { once: true });
 
   const { committed, finished } = navigation.navigate("#1");
@@ -88,7 +88,7 @@
   assert_equals(document.activeElement, decoy, "focus() worked");
 
   navigation.addEventListener("navigate", e => {
-    e.transitionWhile(Promise.resolve());
+    e.intercept();
   }, { once: true });
 
   const { committed, finished } = navigation.navigate("#1");
@@ -111,7 +111,7 @@
   assert_equals(document.activeElement, decoy, "focus() worked");
 
   navigation.addEventListener("navigate", e => {
-    e.transitionWhile(Promise.resolve());
+    e.intercept();
   }, { once: true });
 
   const { committed, finished } = navigation.navigate("#1");
@@ -134,7 +134,7 @@
   assert_equals(document.activeElement, decoy, "focus() worked");
 
   navigation.addEventListener("navigate", e => {
-    e.transitionWhile(Promise.resolve());
+    e.intercept();
   }, { once: true });
 
   const { committed, finished } = navigation.navigate("#1");
@@ -156,7 +156,7 @@
   assert_equals(document.activeElement, decoy, "focus() worked");
 
   navigation.addEventListener("navigate", e => {
-    e.transitionWhile(Promise.resolve());
+    e.intercept();
   }, { once: true });
 
   const { committed, finished } = navigation.navigate("#1");
diff --git a/testing/web-platform/tests/navigation-api/focus-reset/basic.html b/testing/web-platform/tests/navigation-api/focus-reset/basic.html
index 1ffaa022ee4ba..f5a30972b0e54 100644
--- a/testing/web-platform/tests/navigation-api/focus-reset/basic.html
+++ b/testing/web-platform/tests/navigation-api/focus-reset/basic.html
@@ -12,7 +12,7 @@
 
   navigation.addEventListener("navigate", e => {
     assert_throws_js(TypeError, () => {
-      e.transitionWhile(Promise.resolve(), { focusReset: "invalid" });
+      e.intercept({ focusReset: "invalid" });
     });
     throwAssertionHappened = true;
   }, { once: true });
@@ -27,40 +27,37 @@
 
 testFocusWasReset(t => {
   navigation.addEventListener("navigate", e => {
-    e.transitionWhile(Promise.resolve());
+    e.intercept();
   }, { once: true });
 }, "Resets the focus when no focusReset option is provided");
 
 testFocusWasReset(t => {
   navigation.addEventListener("navigate", e => {
-    e.transitionWhile(Promise.resolve());
+    e.intercept();
   }, { once: true });
 }, "Resets the focus when focusReset is explicitly set to undefined");
 
 testFocusWasReset(t => {
   navigation.addEventListener("navigate", e => {
-    e.transitionWhile(new Promise(r => t.step_timeout(r, 5)));
+    e.intercept({ handler: () => new Promise(r => t.step_timeout(r, 5)) });
   }, { once: true });
 }, "Resets the focus when no focusReset option is provided (nontrivial fulfilled promise)");
 
 testFocusWasReset(t => {
   navigation.addEventListener("navigate", e => {
-    e.transitionWhile(Promise.reject());
+    e.intercept({ handler: () => Promise.reject() });
   }, { once: true });
 }, "Resets the focus when no focusReset option is provided (rejected promise)");
 
 testFocusWasReset(t => {
   navigation.addEventListener("navigate", e => {
-    e.transitionWhile(
-      Promise.resolve(),
-      { focusReset: "after-transition" }
-    );
+    e.intercept({ focusReset: "after-transition" });
   }, { once: true });
 }, "Resets the focus when focusReset is explicitly set to 'after-transition'");
 
 testFocusWasNotReset(t => {
   navigation.addEventListener("navigate", e => {
-    e.transitionWhile(Promise.resolve(), { focusReset: "manual" });
+    e.intercept({ focusReset: "manual" });
   });
 }, "Does not reset the focus when focusReset is set to 'manual'");
 </script>
diff --git a/testing/web-platform/tests/navigation-api/focus-reset/change-focus-again-in-blur-during-transitionWhile.html b/testing/web-platform/tests/navigation-api/focus-reset/change-focus-again-in-blur-during-intercept.html
similarity index 83%
rename from testing/web-platform/tests/navigation-api/focus-reset/change-focus-again-in-blur-during-transitionWhile.html
rename to testing/web-platform/tests/navigation-api/focus-reset/change-focus-again-in-blur-during-intercept.html
index 2275ac8e96c37..a7339c97883f6 100644
--- a/testing/web-platform/tests/navigation-api/focus-reset/change-focus-again-in-blur-during-transitionWhile.html
+++ b/testing/web-platform/tests/navigation-api/focus-reset/change-focus-again-in-blur-during-intercept.html
@@ -4,10 +4,10 @@
 <body>
 <script>
 promise_test(async t => {
-  let transitionWhile_resolve;
+  let intercept_resolve;
   navigation.addEventListener("navigate", e => {
-    e.transitionWhile(new Promise(resolve => transitionWhile_resolve = resolve),
-                      { focusReset: "after-transition" });
+    e.intercept({ handler: () => new Promise(resolve => intercept_resolve = resolve),
+                  focusReset: "after-transition" });
   }, { once: true });
 
   const button = document.body.appendChild(document.createElement("button"));
@@ -27,7 +27,7 @@
   button.blur();
   assert_equals(document.activeElement, button2, "focus() in blur worked");
 
-  transitionWhile_resolve();
+  intercept_resolve();
   await finished;
   assert_equals(document.activeElement, button2, "Focus was not reset after the transition");
 }, "");
diff --git a/testing/web-platform/tests/navigation-api/focus-reset/change-focus-back-to-origial-during-transitionWhile.html b/testing/web-platform/tests/navigation-api/focus-reset/change-focus-back-to-origial-during-intercept.html
similarity index 83%
rename from testing/web-platform/tests/navigation-api/focus-reset/change-focus-back-to-origial-during-transitionWhile.html
rename to testing/web-platform/tests/navigation-api/focus-reset/change-focus-back-to-origial-during-intercept.html
index b94ef1e660a98..4e5b9dfb6aa31 100644
--- a/testing/web-platform/tests/navigation-api/focus-reset/change-focus-back-to-origial-during-transitionWhile.html
+++ b/testing/web-platform/tests/navigation-api/focus-reset/change-focus-back-to-origial-during-intercept.html
@@ -4,10 +4,10 @@
 <body>
 <script>
 promise_test(async t => {
-  let transitionWhile_resolve;
+  let intercept_resolve;
   navigation.addEventListener("navigate", e => {
-    e.transitionWhile(new Promise(resolve => transitionWhile_resolve = resolve),
-                      { focusReset: "after-transition" });
+    e.intercept({ handler: () => new Promise(resolve => intercept_resolve = resolve),
+                  focusReset: "after-transition" });
   }, { once: true });
 
   const button = document.body.appendChild(document.createElement("button"));
@@ -28,7 +28,7 @@
   button.focus();
   assert_equals(document.activeElement, button, "focus() worked");
 
-  transitionWhile_resolve();
+  intercept_resolve();
   await finished;
   assert_equals(document.activeElement, button, "Focus was not reset after the transition");
 }, "");
diff --git a/testing/web-platform/tests/navigation-api/focus-reset/change-focus-during-transitionWhile.html b/testing/web-platform/tests/navigation-api/focus-reset/change-focus-during-intercept.html
similarity index 82%
rename from testing/web-platform/tests/navigation-api/focus-reset/change-focus-during-transitionWhile.html
rename to testing/web-platform/tests/navigation-api/focus-reset/change-focus-during-intercept.html
index 6ed4fca6d2b22..0593231a39002 100644
--- a/testing/web-platform/tests/navigation-api/focus-reset/change-focus-during-transitionWhile.html
+++ b/testing/web-platform/tests/navigation-api/focus-reset/change-focus-during-intercept.html
@@ -4,10 +4,10 @@
 <body>
 <script>
 promise_test(async t => {
-  let transitionWhile_resolve;
+  let intercept_resolve;
   navigation.addEventListener("navigate", e => {
-    e.transitionWhile(new Promise(resolve => transitionWhile_resolve = resolve),
-                      { focusReset: "after-transition" });
+    e.intercept({ handler: () => new Promise(resolve => intercept_resolve = resolve),
+                  focusReset: "after-transition" });
   }, { once: true });
 
   const button = document.body.appendChild(document.createElement("button"));
@@ -26,7 +26,7 @@
   button2.focus();
   assert_equals(document.activeElement, button2, "focus() worked");
 
-  transitionWhile_resolve();
+  intercept_resolve();
   await finished;
   assert_equals(document.activeElement, button2, "Focus was not reset after the transition");
 }, "");
diff --git a/testing/web-platform/tests/navigation-api/focus-reset/change-focus-then-remove-during-transitionWhile.html b/testing/web-platform/tests/navigation-api/focus-reset/change-focus-then-remove-during-intercept.html
similarity index 86%
rename from testing/web-platform/tests/navigation-api/focus-reset/change-focus-then-remove-during-transitionWhile.html
rename to testing/web-platform/tests/navigation-api/focus-reset/change-focus-then-remove-during-intercept.html
index 6a90a25eb671a..a5d8062ce085c 100644
--- a/testing/web-platform/tests/navigation-api/focus-reset/change-focus-then-remove-during-transitionWhile.html
+++ b/testing/web-platform/tests/navigation-api/focus-reset/change-focus-then-remove-during-intercept.html
@@ -4,9 +4,10 @@
 <body>
 <script>
 promise_test(async t => {
-  let transitionWhile_resolve;
+  let intercept_resolve;
   navigation.addEventListener("navigate", e => {
-    e.transitionWhile(new Promise(resolve => transitionWhile_resolve = resolve), { focusReset: "after-transition" });
+    e.intercept({ handler: () => new Promise(resolve => intercept_resolve = resolve),
+                  focusReset: "after-transition" });
   }, { once: true });
 
   const button = document.body.appendChild(document.createElement("button"));
@@ -30,7 +31,7 @@
   assert_true(onfocus_called);
 
   document.body.onfocus = t.unreached_func("onfocus shouldn't fire a second time due to focus reset");
-  transitionWhile_resolve();
+  intercept_resolve();
   await finished;
   assert_equals(document.activeElement, document.body, "Focus remains on document.body after promise fulfills");
   await new Promise(resolve => t.step_timeout(resolve, 10));
diff --git a/testing/web-platform/tests/navigation-api/focus-reset/multiple-transitionWhile.html b/testing/web-platform/tests/navigation-api/focus-reset/multiple-intercept.html
similarity index 67%
rename from testing/web-platform/tests/navigation-api/focus-reset/multiple-transitionWhile.html
rename to testing/web-platform/tests/navigation-api/focus-reset/multiple-intercept.html
index 3420991f9a861..75e38c98a40f1 100644
--- a/testing/web-platform/tests/navigation-api/focus-reset/multiple-transitionWhile.html
+++ b/testing/web-platform/tests/navigation-api/focus-reset/multiple-intercept.html
@@ -9,61 +9,61 @@
 
 testFocusWasReset(t => {
   navigation.addEventListener("navigate", e => {
-    e.transitionWhile(Promise.resolve());
+    e.intercept();
   }, { once: true });
 
   navigation.addEventListener("navigate", e => {
-    e.transitionWhile(Promise.resolve(), { focusReset: "after-transition" });
+    e.intercept({ focusReset: "after-transition" });
   }, { once: true });
 }, "(not provided) + after-transition");
 
 testFocusWasNotReset(t => {
   navigation.addEventListener("navigate", e => {
-    e.transitionWhile(Promise.resolve());
+    e.intercept();
   }, { once: true });
 
   navigation.addEventListener("navigate", e => {
-    e.transitionWhile(Promise.resolve(), { focusReset: "manual" });
+    e.intercept({ focusReset: "manual" });
   }, { once: true });
 }, "(not provided) + manual");
 
 testFocusWasNotReset(t => {
   navigation.addEventListener("navigate", e => {
-    e.transitionWhile(Promise.resolve(), { focusReset: "after-transition" });
+    e.intercept({ focusReset: "after-transition" });
   }, { once: true });
 
   navigation.addEventListener("navigate", e => {
-    e.transitionWhile(Promise.resolve(), { focusReset: "manual" });
+    e.intercept({ focusReset: "manual" });
   }, { once: true });
 }, "after-transition + manual");
 
 testFocusWasReset(t => {
   navigation.addEventListener("navigate", e => {
-    e.transitionWhile(Promise.resolve(), { focusReset: "after-transition" });
+    e.intercept({ focusReset: "after-transition" });
   }, { once: true });
 
   navigation.addEventListener("navigate", e => {
-    e.transitionWhile(Promise.resolve());
+    e.intercept();
   }, { once: true });
 }, "after-transition + (not provided)");
 
 testFocusWasReset(t => {
   navigation.addEventListener("navigate", e => {
-    e.transitionWhile(Promise.resolve(), { focusReset: "manual" });
+    e.intercept({ focusReset: "manual" });
   }, { once: true });
 
   navigation.addEventListener("navigate", e => {
-    e.transitionWhile(Promise.resolve(), { focusReset: "after-transition" });
+    e.intercept({ focusReset: "after-transition" });
   }, { once: true });
 }, "manual + after-transition");
 
 testFocusWasNotReset(t => {
   navigation.addEventListener("navigate", e => {
-    e.transitionWhile(Promise.resolve(), { focusReset: "manual" });
+    e.intercept({ focusReset: "manual" });
   }, { once: true });
 
   navigation.addEventListener("navigate", e => {
-    e.transitionWhile(Promise.resolve());
+    e.intercept();
   }, { once: true });
 }, "manual + (not provided)");
 </script>
diff --git a/testing/web-platform/tests/navigation-api/navigate-event/cross-window/click-crossdocument-crossorigin-sameorigindomain.sub.html b/testing/web-platform/tests/navigation-api/navigate-event/cross-window/click-crossdocument-crossorigin-sameorigindomain.sub.html
index d162d8ddb883b..676672a230f15 100644
--- a/testing/web-platform/tests/navigation-api/navigate-event/cross-window/click-crossdocument-crossorigin-sameorigindomain.sub.html
+++ b/testing/web-platform/tests/navigation-api/navigate-event/cross-window/click-crossdocument-crossorigin-sameorigindomain.sub.html
@@ -24,7 +24,7 @@
     iframe.contentWindow.navigation.onnavigate = t.step_func_done(e => {
       assert_equals(e.navigationType, "push", "navigationType");
       assert_true(e.cancelable, "cancelable");
-      assert_true(e.canTransition, "canTransition");
+      assert_true(e.canIntercept, "canIntercept");
       assert_false(e.userInitiated, "userInitiated");
       assert_false(e.hashChange, "hashChange");
       assert_equals(e.formData, null, "formData");
diff --git a/testing/web-platform/tests/navigation-api/navigate-event/cross-window/click-crossdocument-sameorigin.html b/testing/web-platform/tests/navigation-api/navigate-event/cross-window/click-crossdocument-sameorigin.html
index 928d202045e34..41c3ca71eef1d 100644
--- a/testing/web-platform/tests/navigation-api/navigate-event/cross-window/click-crossdocument-sameorigin.html
+++ b/testing/web-platform/tests/navigation-api/navigate-event/cross-window/click-crossdocument-sameorigin.html
@@ -12,7 +12,7 @@
     i.contentWindow.navigation.onnavigate = t.step_func_done(e => {
       assert_equals(e.navigationType, "push", "navigationType");
       assert_true(e.cancelable, "cancelable");
-      assert_true(e.canTransition, "canTransition");
+      assert_true(e.canIntercept, "canIntercept");
       assert_false(e.userInitiated, "userInitiated");
       assert_false(e.hashChange, "hashChange");
       assert_equals(e.formData, null, "formData");
diff --git a/testing/web-platform/tests/navigation-api/navigate-event/cross-window/click-samedocument-crossorigin-sameorigindomain.sub.html b/testing/web-platform/tests/navigation-api/navigate-event/cross-window/click-samedocument-crossorigin-sameorigindomain.sub.html
index b7d284088081e..a467ecf9d73d8 100644
--- a/testing/web-platform/tests/navigation-api/navigate-event/cross-window/click-samedocument-crossorigin-sameorigindomain.sub.html
+++ b/testing/web-platform/tests/navigation-api/navigate-event/cross-window/click-samedocument-crossorigin-sameorigindomain.sub.html
@@ -24,7 +24,7 @@
     iframe.contentWindow.navigation.onnavigate = t.step_func_done(e => {
       assert_equals(e.navigationType, "push", "navigationType");
       assert_true(e.cancelable, "cancelable");
-      assert_true(e.canTransition, "canTransition");
+      assert_true(e.canIntercept, "canIntercept");
       assert_false(e.userInitiated, "userInitiated");
       assert_true(e.hashChange, "hashChange");
       assert_equals(e.formData, null, "formData");
diff --git a/testing/web-platform/tests/navigation-api/navigate-event/cross-window/click-samedocument-crossorigin.html b/testing/web-platform/tests/navigation-api/navigate-event/cross-window/click-samedocument-crossorigin.html
index 32bc4cd291ac6..b9fa97f6d526a 100644
--- a/testing/web-platform/tests/navigation-api/navigate-event/cross-window/click-samedocument-crossorigin.html
+++ b/testing/web-platform/tests/navigation-api/navigate-event/cross-window/click-samedocument-crossorigin.html
@@ -22,7 +22,7 @@
   window.onmessage = t.step_func_done(e => {
     assert_equals(e.data.navigationType, "push", "navigationType");
     assert_true(e.data.cancelable, "cancelable");
-    assert_true(e.data.canTransition, "canTransition");
+    assert_true(e.data.canIntercept, "canIntercept");
     assert_false(e.data.userInitiated, "userInitiated");
     assert_true(e.data.hashChange, "hashChange");
     assert_equals(e.data.formData, null, "formData");
diff --git a/testing/web-platform/tests/navigation-api/navigate-event/cross-window/click-samedocument-sameorigin.html b/testing/web-platform/tests/navigation-api/navigate-event/cross-window/click-samedocument-sameorigin.html
index fc815abb39eb1..566bea3dc7e9b 100644
--- a/testing/web-platform/tests/navigation-api/navigate-event/cross-window/click-samedocument-sameorigin.html
+++ b/testing/web-platform/tests/navigation-api/navigate-event/cross-window/click-samedocument-sameorigin.html
@@ -10,7 +10,7 @@
   i.contentWindow.navigation.onnavigate = t.step_func_done(e => {
     assert_equals(e.navigationType, "push", "navigationType");
     assert_true(e.cancelable, "cancelable");
-    assert_true(e.canTransition, "canTransition");
+    assert_true(e.canIntercept, "canIntercept");
     assert_false(e.userInitiated, "userInitiated");
     assert_true(e.hashChange, "hashChange");
     assert_equals(e.formData, null, "formData");
diff --git a/testing/web-platform/tests/navigation-api/navigate-event/cross-window/location-crossdocument-crossorigin-sameorigindomain.sub.html b/testing/web-platform/tests/navigation-api/navigate-event/cross-window/location-crossdocument-crossorigin-sameorigindomain.sub.html
index 24824b12177d9..77a5873c0838f 100644
--- a/testing/web-platform/tests/navigation-api/navigate-event/cross-window/location-crossdocument-crossorigin-sameorigindomain.sub.html
+++ b/testing/web-platform/tests/navigation-api/navigate-event/cross-window/location-crossdocument-crossorigin-sameorigindomain.sub.html
@@ -17,7 +17,7 @@
     iframe.contentWindow.navigation.onnavigate = t.step_func_done(e => {
       assert_equals(e.navigationType, "push", "navigationType");
       assert_true(e.cancelable, "cancelable");
-      assert_true(e.canTransition, "canTransition");
+      assert_true(e.canIntercept, "canIntercept");
       assert_false(e.userInitiated, "userInitiated");
       assert_false(e.hashChange, "hashChange");
       assert_equals(e.formData, null, "formData");
diff --git a/testing/web-platform/tests/navigation-api/navigate-event/cross-window/location-crossdocument-sameorigin.html b/testing/web-platform/tests/navigation-api/navigate-event/cross-window/location-crossdocument-sameorigin.html
index 1ac3eef874770..41ac1b037506f 100644
--- a/testing/web-platform/tests/navigation-api/navigate-event/cross-window/location-crossdocument-sameorigin.html
+++ b/testing/web-platform/tests/navigation-api/navigate-event/cross-window/location-crossdocument-sameorigin.html
@@ -9,7 +9,7 @@
   i.contentWindow.navigation.onnavigate = t.step_func_done(e => {
     assert_equals(e.navigationType, "push", "navigationType");
     assert_true(e.cancelable, "cancelable");
-    assert_true(e.canTransition, "canTransition");
+    assert_true(e.canIntercept, "canIntercept");
     assert_false(e.userInitiated, "userInitiated");
     assert_false(e.hashChange, "hashChange");
     assert_equals(e.formData, null, "formData");
diff --git a/testing/web-platform/tests/navigation-api/navigate-event/cross-window/location-samedocument-crossorigin-sameorigindomain.sub.html b/testing/web-platform/tests/navigation-api/navigate-event/cross-window/location-samedocument-crossorigin-sameorigindomain.sub.html
index 96032c14ac60a..1eda74e982831 100644
--- a/testing/web-platform/tests/navigation-api/navigate-event/cross-window/location-samedocument-crossorigin-sameorigindomain.sub.html
+++ b/testing/web-platform/tests/navigation-api/navigate-event/cross-window/location-samedocument-crossorigin-sameorigindomain.sub.html
@@ -17,7 +17,7 @@
     iframe.contentWindow.navigation.onnavigate = t.step_func_done(e => {
       assert_equals(e.navigationType, "push", "navigationType");
       assert_true(e.cancelable, "cancelable");
-      assert_true(e.canTransition, "canTransition");
+      assert_true(e.canIntercept, "canIntercept");
       assert_false(e.userInitiated, "userInitiated");
       assert_true(e.hashChange, "hashChange");
       assert_equals(e.formData, null, "formData");
diff --git a/testing/web-platform/tests/navigation-api/navigate-event/cross-window/location-samedocument-crossorigin.html b/testing/web-platform/tests/navigation-api/navigate-event/cross-window/location-samedocument-crossorigin.html
index 8a58be7a2b412..5679236a7ddca 100644
--- a/testing/web-platform/tests/navigation-api/navigate-event/cross-window/location-samedocument-crossorigin.html
+++ b/testing/web-platform/tests/navigation-api/navigate-event/cross-window/location-samedocument-crossorigin.html
@@ -15,7 +15,7 @@
   window.onmessage = t.step_func_done(e => {
     assert_equals(e.data.navigationType, "push", "navigationType");
     assert_true(e.data.cancelable, "cancelable");
-    assert_true(e.data.canTransition, "canTransition");
+    assert_true(e.data.canIntercept, "canIntercept");
     assert_false(e.data.userInitiated, "userInitiated");
     assert_true(e.data.hashChange, "hashChange");
     assert_equals(e.data.formData, null, "formData");
diff --git a/testing/web-platform/tests/navigation-api/navigate-event/cross-window/location-samedocument-sameorigin.html b/testing/web-platform/tests/navigation-api/navigate-event/cross-window/location-samedocument-sameorigin.html
index 3901b9ddbccc4..a7e4181c3a19f 100644
--- a/testing/web-platform/tests/navigation-api/navigate-event/cross-window/location-samedocument-sameorigin.html
+++ b/testing/web-platform/tests/navigation-api/navigate-event/cross-window/location-samedocument-sameorigin.html
@@ -9,7 +9,7 @@
   i.contentWindow.navigation.onnavigate = t.step_func_done(e => {
     assert_equals(e.navigationType, "push", "navigationType");
     assert_true(e.cancelable, "cancelable");
-    assert_true(e.canTransition, "canTransition");
+    assert_true(e.canIntercept, "canIntercept");
     assert_false(e.userInitiated, "userInitiated");
     assert_true(e.hashChange, "hashChange");
     assert_equals(e.formData, null, "formData");
diff --git a/testing/web-platform/tests/navigation-api/navigate-event/cross-window/open-crossdocument-crossorigin-sameorigindomain.sub.html b/testing/web-platform/tests/navigation-api/navigate-event/cross-window/open-crossdocument-crossorigin-sameorigindomain.sub.html
index d386e487a333c..ea9ea479c3473 100644
--- a/testing/web-platform/tests/navigation-api/navigate-event/cross-window/open-crossdocument-crossorigin-sameorigindomain.sub.html
+++ b/testing/web-platform/tests/navigation-api/navigate-event/cross-window/open-crossdocument-crossorigin-sameorigindomain.sub.html
@@ -18,7 +18,7 @@
     iframe.contentWindow.navigation.onnavigate = t.step_func_done(e => {
       assert_equals(e.navigationType, "push", "navigationType");
       assert_true(e.cancelable, "cancelable");
-      assert_true(e.canTransition, "canTransition");
+      assert_true(e.canIntercept, "canIntercept");
       assert_false(e.userInitiated, "userInitiated");
       assert_false(e.hashChange, "hashChange");
       assert_equals(e.formData, null, "formData");
diff --git a/testing/web-platform/tests/navigation-api/navigate-event/cross-window/open-crossdocument-sameorigin.html b/testing/web-platform/tests/navigation-api/navigate-event/cross-window/open-crossdocument-sameorigin.html
index a899dd86a3a77..478483e238d72 100644
--- a/testing/web-platform/tests/navigation-api/navigate-event/cross-window/open-crossdocument-sameorigin.html
+++ b/testing/web-platform/tests/navigation-api/navigate-event/cross-window/open-crossdocument-sameorigin.html
@@ -9,7 +9,7 @@
   i.contentWindow.navigation.onnavigate = t.step_func_done(e => {
     assert_equals(e.navigationType, "push", "navigationType");
     assert_true(e.cancelable, "cancelable");
-    assert_true(e.canTransition, "canTransition");
+    assert_true(e.canIntercept, "canIntercept");
     assert_false(e.userInitiated, "userInitiated");
     assert_false(e.hashChange, "hashChange");
     assert_equals(e.formData, null, "formData");
diff --git a/testing/web-platform/tests/navigation-api/navigate-event/cross-window/open-samedocument-crossorigin-sameorigindomain.sub.html b/testing/web-platform/tests/navigation-api/navigate-event/cross-window/open-samedocument-crossorigin-sameorigindomain.sub.html
index b44303c18b8b8..324adb32a4592 100644
--- a/testing/web-platform/tests/navigation-api/navigate-event/cross-window/open-samedocument-crossorigin-sameorigindomain.sub.html
+++ b/testing/web-platform/tests/navigation-api/navigate-event/cross-window/open-samedocument-crossorigin-sameorigindomain.sub.html
@@ -18,7 +18,7 @@
     iframe.contentWindow.navigation.onnavigate = t.step_func_done(e => {
       assert_equals(e.navigationType, "push", "navigationType");
       assert_true(e.cancelable, "cancelable");
-      assert_true(e.canTransition, "canTransition");
+      assert_true(e.canIntercept, "canIntercept");
       assert_false(e.userInitiated, "userInitiated");
       assert_true(e.hashChange, "hashChange");
       assert_equals(e.formData, null, "formData");
diff --git a/testing/web-platform/tests/navigation-api/navigate-event/cross-window/open-samedocument-crossorigin.html b/testing/web-platform/tests/navigation-api/navigate-event/cross-window/open-samedocument-crossorigin.html
index 65f062fcd578b..23dceb0420484 100644
--- a/testing/web-platform/tests/navigation-api/navigate-event/cross-window/open-samedocument-crossorigin.html
+++ b/testing/web-platform/tests/navigation-api/navigate-event/cross-window/open-samedocument-crossorigin.html
@@ -16,7 +16,7 @@
   window.onmessage = t.step_func_done(e => {
     assert_equals(e.data.navigationType, "push", "navigationType");
     assert_true(e.data.cancelable, "cancelable");
-    assert_true(e.data.canTransition, "canTransition");
+    assert_true(e.data.canIntercept, "canIntercept");
     assert_false(e.data.userInitiated, "userInitiated");
     assert_true(e.data.hashChange, "hashChange");
     assert_equals(e.data.formData, null, "formData");
diff --git a/testing/web-platform/tests/navigation-api/navigate-event/cross-window/open-samedocument-sameorigin.html b/testing/web-platform/tests/navigation-api/navigate-event/cross-window/open-samedocument-sameorigin.html
index 3f3c38d85062d..9ca853180343f 100644
--- a/testing/web-platform/tests/navigation-api/navigate-event/cross-window/open-samedocument-sameorigin.html
+++ b/testing/web-platform/tests/navigation-api/navigate-event/cross-window/open-samedocument-sameorigin.html
@@ -9,7 +9,7 @@
   i.contentWindow.navigation.onnavigate = t.step_func_done(e => {
     assert_equals(e.navigationType, "push", "navigationType");
     assert_true(e.cancelable, "cancelable");
-    assert_true(e.canTransition, "canTransition");
+    assert_true(e.canIntercept, "canIntercept");
     assert_false(e.userInitiated, "userInitiated");
     assert_true(e.hashChange, "hashChange");
     assert_equals(e.formData, null, "formData");
diff --git a/testing/web-platform/tests/navigation-api/navigate-event/cross-window/resources/cross-origin-iframe-helper.html b/testing/web-platform/tests/navigation-api/navigate-event/cross-window/resources/cross-origin-iframe-helper.html
index 96e8a0c1e6543..3393a2ecaa9e6 100644
--- a/testing/web-platform/tests/navigation-api/navigate-event/cross-window/resources/cross-origin-iframe-helper.html
+++ b/testing/web-platform/tests/navigation-api/navigate-event/cross-window/resources/cross-origin-iframe-helper.html
@@ -1,9 +1,10 @@
+<!DOCTYPE html>
 <script>
 navigation.onnavigate = e => {
   const message = {
     navigationType: e.navigationType,
     cancelable: e.cancelable,
-    canTransition: e.canTransition,
+    canIntercept: e.canIntercept,
     userInitiated: e.userInitiated,
     hashChange: e.hashChange,
     formData: e.formData,
diff --git a/testing/web-platform/tests/navigation-api/navigate-event/cross-window/submit-crossdocument-crossorigin-sameorigindomain.sub.html b/testing/web-platform/tests/navigation-api/navigate-event/cross-window/submit-crossdocument-crossorigin-sameorigindomain.sub.html
index 36101a400041b..f611034617401 100644
--- a/testing/web-platform/tests/navigation-api/navigate-event/cross-window/submit-crossdocument-crossorigin-sameorigindomain.sub.html
+++ b/testing/web-platform/tests/navigation-api/navigate-event/cross-window/submit-crossdocument-crossorigin-sameorigindomain.sub.html
@@ -24,7 +24,7 @@
     iframe.contentWindow.navigation.onnavigate = t.step_func_done(e => {
       assert_equals(e.navigationType, "push", "navigationType");
       assert_true(e.cancelable, "cancelable");
-      assert_true(e.canTransition, "canTransition");
+      assert_true(e.canIntercept, "canIntercept");
       assert_false(e.userInitiated, "userInitiated");
       assert_false(e.hashChange, "hashChange");
       assert_equals(e.formData, null, "formData");
diff --git a/testing/web-platform/tests/navigation-api/navigate-event/cross-window/submit-crossdocument-sameorigin.html b/testing/web-platform/tests/navigation-api/navigate-event/cross-window/submit-crossdocument-sameorigin.html
index 93b97351d752c..05347335a192a 100644
--- a/testing/web-platform/tests/navigation-api/navigate-event/cross-window/submit-crossdocument-sameorigin.html
+++ b/testing/web-platform/tests/navigation-api/navigate-event/cross-window/submit-crossdocument-sameorigin.html
@@ -10,7 +10,7 @@
   i.contentWindow.navigation.onnavigate = t.step_func_done(e => {
     assert_equals(e.navigationType, "push", "navigationType");
     assert_true(e.cancelable, "cancelable");
-    assert_true(e.canTransition, "canTransition");
+    assert_true(e.canIntercept, "canIntercept");
     assert_false(e.userInitiated, "userInitiated");
     assert_false(e.hashChange, "hashChange");
     assert_equals(e.formData, null, "formData");
diff --git a/testing/web-platform/tests/navigation-api/navigate-event/cross-window/submit-samedocument-crossorigin-sameorigindomain.sub.html b/testing/web-platform/tests/navigation-api/navigate-event/cross-window/submit-samedocument-crossorigin-sameorigindomain.sub.html
index 9f5ba8b44afc3..9e64a0124daf5 100644
--- a/testing/web-platform/tests/navigation-api/navigate-event/cross-window/submit-samedocument-crossorigin-sameorigindomain.sub.html
+++ b/testing/web-platform/tests/navigation-api/navigate-event/cross-window/submit-samedocument-crossorigin-sameorigindomain.sub.html
@@ -24,7 +24,7 @@
     iframe.contentWindow.navigation.onnavigate = t.step_func_done(e => {
       assert_equals(e.navigationType, "push", "navigationType");
       assert_true(e.cancelable, "cancelable");
-      assert_true(e.canTransition, "canTransition");
+      assert_true(e.canIntercept, "canIntercept");
       assert_false(e.userInitiated, "userInitiated");
       assert_true(e.hashChange, "hashChange");
       assert_equals(e.formData, null, "formData");
diff --git a/testing/web-platform/tests/navigation-api/navigate-event/cross-window/submit-samedocument-crossorigin.html b/testing/web-platform/tests/navigation-api/navigate-event/cross-window/submit-samedocument-crossorigin.html
index 51a313ac18147..e53a1f93e7a7a 100644
--- a/testing/web-platform/tests/navigation-api/navigate-event/cross-window/submit-samedocument-crossorigin.html
+++ b/testing/web-platform/tests/navigation-api/navigate-event/cross-window/submit-samedocument-crossorigin.html
@@ -22,7 +22,7 @@
   window.onmessage = t.step_func_done(e => {
     assert_equals(e.data.navigationType, "push", "navigationType");
     assert_true(e.data.cancelable, "cancelable");
-    assert_true(e.data.canTransition, "canTransition");
+    assert_true(e.data.canIntercept, "canIntercept");
     assert_false(e.data.userInitiated, "userInitiated");
     assert_true(e.data.hashChange, "hashChange");
     assert_equals(e.data.formData, null, "formData");
diff --git a/testing/web-platform/tests/navigation-api/navigate-event/cross-window/submit-samedocument-sameorigin.html b/testing/web-platform/tests/navigation-api/navigate-event/cross-window/submit-samedocument-sameorigin.html
index f0b7b7393711a..43aa3226fcd6f 100644
--- a/testing/web-platform/tests/navigation-api/navigate-event/cross-window/submit-samedocument-sameorigin.html
+++ b/testing/web-platform/tests/navigation-api/navigate-event/cross-window/submit-samedocument-sameorigin.html
@@ -10,7 +10,7 @@
   i.contentWindow.navigation.onnavigate = t.step_func_done(e => {
     assert_equals(e.navigationType, "push", "navigationType");
     assert_true(e.cancelable, "cancelable");
-    assert_true(e.canTransition, "canTransition");
+    assert_true(e.canIntercept, "canIntercept");
     assert_false(e.userInitiated, "userInitiated");
     assert_true(e.hashChange, "hashChange");
     assert_equals(e.formData, null, "formData");
diff --git a/testing/web-platform/tests/navigation-api/navigate-event/event-constructor.html b/testing/web-platform/tests/navigation-api/navigate-event/event-constructor.html
index 17c89dedd1a30..065884240e092 100644
--- a/testing/web-platform/tests/navigation-api/navigate-event/event-constructor.html
+++ b/testing/web-platform/tests/navigation-api/navigate-event/event-constructor.html
@@ -12,7 +12,7 @@
   assert_throws_js(TypeError, () => {
     new NavigateEvent("navigate", {
       navigationType: "push",
-      canTransition: false,
+      canIntercept: false,
       userInitiated: false,
       hashChange: false,
       signal: (new AbortController()).signal,
@@ -30,7 +30,7 @@
       new NavigateEvent("navigate", {
         navigationType: "push",
         destination: e.destination,
-        canTransition: false,
+        canIntercept: false,
         userInitiated: false,
         hashChange: false,
         formData: null,
@@ -53,7 +53,7 @@
     const event = new NavigateEvent("navigate", {
       navigationType: "replace",
       destination: e.destination,
-      canTransition: true,
+      canIntercept: true,
       userInitiated: true,
       hashChange: true,
       signal,
@@ -64,7 +64,7 @@
 
     assert_equals(event.navigationType, "replace");
     assert_equals(event.destination, e.destination);
-    assert_equals(event.canTransition, true);
+    assert_equals(event.canIntercept, true);
     assert_equals(event.userInitiated, true);
     assert_equals(event.hashChange, true);
     assert_equals(event.signal, signal);
@@ -84,7 +84,7 @@
     });
 
     assert_equals(event.navigationType, "push");
-    assert_equals(event.canTransition, false);
+    assert_equals(event.canIntercept, false);
     assert_equals(event.userInitiated, false);
     assert_equals(event.hashChange, false);
     assert_equals(event.formData, null);
diff --git a/testing/web-platform/tests/navigation-api/navigate-event/transitionWhile-after-dispatch.html b/testing/web-platform/tests/navigation-api/navigate-event/intercept-after-dispatch.html
similarity index 70%
rename from testing/web-platform/tests/navigation-api/navigate-event/transitionWhile-after-dispatch.html
rename to testing/web-platform/tests/navigation-api/navigate-event/intercept-after-dispatch.html
index 910665cb3deb5..abb328050d880 100644
--- a/testing/web-platform/tests/navigation-api/navigate-event/transitionWhile-after-dispatch.html
+++ b/testing/web-platform/tests/navigation-api/navigate-event/intercept-after-dispatch.html
@@ -7,10 +7,10 @@
   navigation.onnavigate = t.step_func(e => {
     t.step_timeout(t.step_func_done(() => {
       assert_equals(e.eventPhase, Event.NONE);
-      assert_throws_dom("InvalidStateError", () => e.transitionWhile(Promise.resolve()));
+      assert_throws_dom("InvalidStateError", () => e.intercept());
     }), 0);
   });
 
   location.href = "#1";
-}, "event.transitionWhile() throws if used after the dispatch phase");
+}, "event.intercept() throws if used after the dispatch phase");
 </script>
diff --git a/testing/web-platform/tests/navigation-api/navigate-event/transitionWhile-and-navigate.html b/testing/web-platform/tests/navigation-api/navigate-event/intercept-and-navigate.html
similarity index 81%
rename from testing/web-platform/tests/navigation-api/navigate-event/transitionWhile-and-navigate.html
rename to testing/web-platform/tests/navigation-api/navigate-event/intercept-and-navigate.html
index f226371d79b35..dfbb67b6b6b1c 100644
--- a/testing/web-platform/tests/navigation-api/navigate-event/transitionWhile-and-navigate.html
+++ b/testing/web-platform/tests/navigation-api/navigate-event/intercept-and-navigate.html
@@ -8,7 +8,7 @@
   await new Promise(r => window.onload = () => t.step_timeout(r, 0));
   await navigation.navigate("#1").finished;
 
-  navigation.onnavigate = e => e.transitionWhile(Promise.resolve());
+  navigation.onnavigate = e => e.intercept();
   navigation.oncurrententrychange = e => {
     if (e.navigationType == "traverse") {
       assert_equals(location.hash, "");
@@ -23,5 +23,5 @@
   await promise_rejects_dom(t, "AbortError", back_result.finished);
   assert_equals(navigation.currentEntry.index, 1);
   assert_equals(navigation.entries().length, 2);
-}, "Using transitionWhile() then navigate() in the ensuing currententrychange should abort the finished promise (but not the committed promise)");
+}, "Using intercept() then navigate() in the ensuing currententrychange should abort the finished promise (but not the committed promise)");
 </script>
diff --git a/testing/web-platform/tests/navigation-api/navigate-event/transitionWhile-canceled-event.html b/testing/web-platform/tests/navigation-api/navigate-event/intercept-canceled-event.html
similarity index 72%
rename from testing/web-platform/tests/navigation-api/navigate-event/transitionWhile-canceled-event.html
rename to testing/web-platform/tests/navigation-api/navigate-event/intercept-canceled-event.html
index f1fe3ece38bf2..d4b9633c1a37c 100644
--- a/testing/web-platform/tests/navigation-api/navigate-event/transitionWhile-canceled-event.html
+++ b/testing/web-platform/tests/navigation-api/navigate-event/intercept-canceled-event.html
@@ -7,11 +7,11 @@
   let assertionHappened = false;
   navigation.onnavigate = t.step_func_done(e => {
     e.preventDefault();
-    assert_throws_dom("InvalidStateError", () => e.transitionWhile(Promise.resolve()));
+    assert_throws_dom("InvalidStateError", () => e.intercept());
     assertionHappened = true;
   });
 
   location.href = "#1";
   assert_true(assertionHappened);
-}, "event.transitionWhile() throws if used on a canceled event");
+}, "event.intercept() throws if used on a canceled event");
 </script>
diff --git a/testing/web-platform/tests/navigation-api/navigate-event/transitionWhile-cross-document-same-origin.html b/testing/web-platform/tests/navigation-api/navigate-event/intercept-cross-document-same-origin.html
similarity index 73%
rename from testing/web-platform/tests/navigation-api/navigate-event/transitionWhile-cross-document-same-origin.html
rename to testing/web-platform/tests/navigation-api/navigate-event/intercept-cross-document-same-origin.html
index 9e55958c53378..0d610cce4f507 100644
--- a/testing/web-platform/tests/navigation-api/navigate-event/transitionWhile-cross-document-same-origin.html
+++ b/testing/web-platform/tests/navigation-api/navigate-event/intercept-cross-document-same-origin.html
@@ -7,13 +7,15 @@
   let target_url = location.href + "?1";
   navigation.onnavigate = t.step_func_done(e => {
     assert_true(e.cancelable);
-    assert_true(e.canTransition);
+    assert_true(e.canIntercept);
     assert_false(e.userInitiated);
     assert_false(e.hashChange);
-    e.transitionWhile(Promise.resolve().then(
-      t.step_func_done(() => assert_equals(location.href, target_url))));
+    e.intercept({ handler: async () => {
+      await Promise.resolve();
+      t.step_func_done(() => assert_equals(location.href, target_url));
+    }});
   });
 
   window.onload = t.step_func(() => location.href = target_url);
-}, "event.transitionWhile() intercepts a same-origin cross-document navigation");
+}, "event.intercept() intercepts a same-origin cross-document navigation");
 </script>
diff --git a/testing/web-platform/tests/navigation-api/navigate-event/transitionWhile-cross-origin.html b/testing/web-platform/tests/navigation-api/navigate-event/intercept-cross-origin.html
similarity index 70%
rename from testing/web-platform/tests/navigation-api/navigate-event/transitionWhile-cross-origin.html
rename to testing/web-platform/tests/navigation-api/navigate-event/intercept-cross-origin.html
index e53371a96a2ce..b367df546c6a7 100644
--- a/testing/web-platform/tests/navigation-api/navigate-event/transitionWhile-cross-origin.html
+++ b/testing/web-platform/tests/navigation-api/navigate-event/intercept-cross-origin.html
@@ -6,13 +6,13 @@
 async_test(t => {
   navigation.onnavigate = t.step_func_done(e => {
     assert_true(e.cancelable);
-    assert_false(e.canTransition);
+    assert_false(e.canIntercept);
     assert_false(e.userInitiated);
     assert_false(e.hashChange);
-    assert_throws_dom("SecurityError", () => e.transitionWhile(Promise.resolve()));
+    assert_throws_dom("SecurityError", () => e.intercept());
     e.preventDefault();
   });
 
   window.onload = t.step_func(() => location.href = get_host_info().HTTPS_REMOTE_ORIGIN);
-}, "event.transitionWhile() should throw if called for a cross origin navigation");
+}, "event.intercept() should throw if called for a cross origin navigation");
 </script>
diff --git a/testing/web-platform/tests/navigation-api/navigate-event/intercept-detach-multiple.html b/testing/web-platform/tests/navigation-api/navigate-event/intercept-detach-multiple.html
new file mode 100644
index 0000000000000..5b6a62328491a
--- /dev/null
+++ b/testing/web-platform/tests/navigation-api/navigate-event/intercept-detach-multiple.html
@@ -0,0 +1,18 @@
+<!doctype html>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<iframe id="i" src="/common/blank.html"></iframe>
+<script>
+async_test(t => {
+  window.onload = t.step_func(() => {
+    let second_handler_run = false;
+    i.contentWindow.navigation.onnavigate = e => {
+      e.intercept({ handler() { i.remove(); }});
+      e.intercept({ handler() { second_handler_run = true; }});
+    };
+
+    i.contentWindow.location.href = "#1";
+    t.step_timeout(t.step_func_done(() => assert_true(second_handler_run)), 0);
+  });
+}, "event.intercept() throws if used on an event from a detached iframe");
+</script>
diff --git a/testing/web-platform/tests/navigation-api/navigate-event/transitionWhile-detach.html b/testing/web-platform/tests/navigation-api/navigate-event/intercept-detach.html
similarity index 80%
rename from testing/web-platform/tests/navigation-api/navigate-event/transitionWhile-detach.html
rename to testing/web-platform/tests/navigation-api/navigate-event/intercept-detach.html
index 25159850803d8..b5ce45aa29c38 100644
--- a/testing/web-platform/tests/navigation-api/navigate-event/transitionWhile-detach.html
+++ b/testing/web-platform/tests/navigation-api/navigate-event/intercept-detach.html
@@ -8,10 +8,10 @@
     i.contentWindow.navigation.onnavigate = t.step_func_done(e => {
       let iframe_constructor = i.contentWindow.DOMException;
       i.remove();
-      assert_throws_dom("InvalidStateError", iframe_constructor, () => e.transitionWhile(Promise.resolve()));
+      assert_throws_dom("InvalidStateError", iframe_constructor, () => e.intercept());
     });
 
     i.contentWindow.location.href = "#1";
   });
-}, "event.transitionWhile() throws if used on an event from a detached iframe");
+}, "event.intercept() throws if used on an event from a detached iframe");
 </script>
diff --git a/testing/web-platform/tests/navigation-api/navigate-event/intercept-handler-null-or-undefined.html b/testing/web-platform/tests/navigation-api/navigate-event/intercept-handler-null-or-undefined.html
new file mode 100644
index 0000000000000..7f5bd6b19f834
--- /dev/null
+++ b/testing/web-platform/tests/navigation-api/navigate-event/intercept-handler-null-or-undefined.html
@@ -0,0 +1,21 @@
+<!doctype html>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script>
+async_test(t => {
+  navigation.onnavigate = t.step_func_done(e => {
+    assert_throws_js(TypeError, () => e.intercept({ handler: null }));
+  });
+
+  location.href = "#1";
+  assert_equals(location.hash, "#1");
+}, "event.intercept() should throw if the handler is null");
+
+async_test(t => {
+  navigation.onnavigatesuccess = t.step_func_done(e => {});
+  navigation.onnavigate = e =>  e.intercept({ handler: undefined });
+
+  location.href = "#2";
+  assert_equals(location.hash, "#2");
+}, "event.intercept() should not throw if the handler is explicit undefined");
+</script>
diff --git a/testing/web-platform/tests/navigation-api/navigate-event/intercept-handler-returns-non-promise.html b/testing/web-platform/tests/navigation-api/navigate-event/intercept-handler-returns-non-promise.html
new file mode 100644
index 0000000000000..96116e929533f
--- /dev/null
+++ b/testing/web-platform/tests/navigation-api/navigate-event/intercept-handler-returns-non-promise.html
@@ -0,0 +1,18 @@
+<!doctype html>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script>
+async_test(t => {
+  navigation.onnavigatesuccess = t.step_func_done(e => {
+    assert_equals(location.hash, "#1");
+    assert_equals(e.constructor, Event);
+    assert_false(e.bubbles);
+    assert_false(e.cancelable);
+  });
+  navigation.onnavigateerror = t.step_func_done(assert_unreached);
+  navigation.onnavigate = e => e.intercept({ handler() { return "123"; }});
+
+  location.href = "#1";
+  assert_equals(location.hash, "#1");
+}, "event.intercept() should resolve immediately if the handler doesn't return a promise");
+</script>
diff --git a/testing/web-platform/tests/navigation-api/navigate-event/transitionWhile-reject.html b/testing/web-platform/tests/navigation-api/navigate-event/intercept-handler-throws.html
similarity index 82%
rename from testing/web-platform/tests/navigation-api/navigate-event/transitionWhile-reject.html
rename to testing/web-platform/tests/navigation-api/navigate-event/intercept-handler-throws.html
index 28864b38a5186..769f675999747 100644
--- a/testing/web-platform/tests/navigation-api/navigate-event/transitionWhile-reject.html
+++ b/testing/web-platform/tests/navigation-api/navigate-event/intercept-handler-throws.html
@@ -17,10 +17,10 @@
     assert_greater_than(e.lineno, 0);
   });
   navigation.onnavigate = e => {
-    e.transitionWhile(new Promise((resolve, reject) => t.step_timeout(() => reject(err), 0)));
+    e.intercept({ handler() { throw err; }});
   };
 
   location.href = "#1";
   assert_equals(location.hash, "#1");
-}, "event.transitionWhile() should abort if the given promise rejects");
+}, "event.intercept() should abort if the handler throws");
 </script>
diff --git a/testing/web-platform/tests/navigation-api/navigate-event/transitionWhile-history-pushState.html b/testing/web-platform/tests/navigation-api/navigate-event/intercept-history-pushState.html
similarity index 78%
rename from testing/web-platform/tests/navigation-api/navigate-event/transitionWhile-history-pushState.html
rename to testing/web-platform/tests/navigation-api/navigate-event/intercept-history-pushState.html
index a08e4ea282376..aad08b742ef4a 100644
--- a/testing/web-platform/tests/navigation-api/navigate-event/transitionWhile-history-pushState.html
+++ b/testing/web-platform/tests/navigation-api/navigate-event/intercept-history-pushState.html
@@ -5,19 +5,19 @@
 async_test(t => {
   let start_length = history.length;
   navigation.onnavigate = t.step_func(e => {
-    e.transitionWhile(new Promise(resolve => t.step_timeout(() => {
-      resolve();
+    e.intercept({ handler: async () => {
+      await new Promise(r => t.step_timeout(r, 0));
       t.step_timeout(t.step_func_done(() => {
         assert_equals(location.hash, "#1");
         assert_equals(history.state, "update");
         assert_equals(history.length, start_length + 1);
       }, 0));
-    }, 0)));
+    }});
   });
 
   history.pushState("update", "", "#1");
   assert_equals(location.hash, "#1");
   assert_equals(history.state, "update");
   assert_equals(history.length, start_length + 1);
-}, "event.transitionWhile() should proceed if the given promise resolves");
+}, "event.intercept() should proceed if the given promise resolves");
 </script>
diff --git a/testing/web-platform/tests/navigation-api/navigate-event/transitionWhile-history-replaceState.html b/testing/web-platform/tests/navigation-api/navigate-event/intercept-history-replaceState.html
similarity index 78%
rename from testing/web-platform/tests/navigation-api/navigate-event/transitionWhile-history-replaceState.html
rename to testing/web-platform/tests/navigation-api/navigate-event/intercept-history-replaceState.html
index e575876de245b..16edec8596e44 100644
--- a/testing/web-platform/tests/navigation-api/navigate-event/transitionWhile-history-replaceState.html
+++ b/testing/web-platform/tests/navigation-api/navigate-event/intercept-history-replaceState.html
@@ -5,19 +5,19 @@
 async_test(t => {
   let start_length = history.length;
   navigation.onnavigate = t.step_func(e => {
-    e.transitionWhile(new Promise(resolve => t.step_timeout(() => {
-      resolve();
+    e.intercept({ handler: async () => {
+      await new Promise(r => t.step_timeout(r, 0));
       t.step_timeout(t.step_func_done(() => {
         assert_equals(location.hash, "#1");
         assert_equals(history.state, "update");
         assert_equals(history.length, start_length);
       }, 0));
-    }, 0)));
+    }});
   });
 
   history.replaceState("update", "", "#1");
   assert_equals(location.hash, "#1");
   assert_equals(history.state, "update");
   assert_equals(history.length, start_length);
-}, "event.transitionWhile() should proceed if the given promise resolves");
+}, "event.intercept() should proceed if the given promise resolves");
 </script>
diff --git a/testing/web-platform/tests/navigation-api/navigate-event/transitionWhile-multiple-times-reject.html b/testing/web-platform/tests/navigation-api/navigate-event/intercept-multiple-times-reject.html
similarity index 75%
rename from testing/web-platform/tests/navigation-api/navigate-event/transitionWhile-multiple-times-reject.html
rename to testing/web-platform/tests/navigation-api/navigate-event/intercept-multiple-times-reject.html
index 0532d755fd343..0b0f1f0b8e838 100644
--- a/testing/web-platform/tests/navigation-api/navigate-event/transitionWhile-multiple-times-reject.html
+++ b/testing/web-platform/tests/navigation-api/navigate-event/intercept-multiple-times-reject.html
@@ -20,9 +20,12 @@
     assert_greater_than(e.lineno, 0);
   });
   navigation.onnavigate = t.step_func(e => {
-    e.transitionWhile(Promise.resolve());
-    e.transitionWhile(new Promise((resolve, reject) => t.step_timeout(() => reject(err), 1)));
-    e.transitionWhile(new Promise(resolve => t.step_timeout(resolve, 1)));
+    e.intercept();
+    e.intercept({ handler: async () => {
+      await new Promise(r => t.step_timeout(r, 1));
+      return Promise.reject(err);
+    }});
+    e.intercept({ handler: () => new Promise(resolve => t.step_timeout(resolve, 1)) });
   });
 
   await navigation.navigate("#1").finished.catch(t.step_func(e => {
@@ -31,5 +34,5 @@
   }));
   assert_true(onnavigateerror_called);
   assert_true(caught_rejection);
-}, "event.transitionWhile() is called multiple times and one of the promises rejects");
+}, "event.intercept() is called multiple times and one of the promises rejects");
 </script>
diff --git a/testing/web-platform/tests/navigation-api/navigate-event/transitionWhile-multiple-times.html b/testing/web-platform/tests/navigation-api/navigate-event/intercept-multiple-times.html
similarity index 69%
rename from testing/web-platform/tests/navigation-api/navigate-event/transitionWhile-multiple-times.html
rename to testing/web-platform/tests/navigation-api/navigate-event/intercept-multiple-times.html
index d5661a54eba39..6deaeeb507de7 100644
--- a/testing/web-platform/tests/navigation-api/navigate-event/transitionWhile-multiple-times.html
+++ b/testing/web-platform/tests/navigation-api/navigate-event/intercept-multiple-times.html
@@ -7,24 +7,24 @@
   let p2_resolved = false;
   let p3_resolved = false;
   navigation.onnavigate = t.step_func(e => {
-    let p1 = Promise.resolve().then(t.step_func(() => {
+    e.intercept({ handler: async () => {
+      await Promise.resolve();
       assert_false(p2_resolved);
       assert_false(p3_resolved);
       p1_resolved = true;
-    }));
-    let p2 = new Promise(resolve => t.step_timeout(resolve, 1)).then(t.step_func(() => {
+    }});
+    e.intercept({ handler: async () => {
+      await new Promise(resolve => t.step_timeout(resolve, 1));
       assert_true(p1_resolved);
       assert_false(p3_resolved);
       p2_resolved = true;
-    }));
-    let p3 = new Promise(resolve => t.step_timeout(resolve, 1)).then(t.step_func(() => {
+    }});
+    e.intercept({ handler: async () => {
+      await new Promise(resolve => t.step_timeout(resolve, 1));
       assert_true(p1_resolved);
       assert_true(p2_resolved);
       p3_resolved = true;
-    }));
-    e.transitionWhile(p1);
-    e.transitionWhile(p2);
-    e.transitionWhile(p3);
+    }});
   });
 
   let promise = navigation.navigate("#1").finished;
@@ -37,5 +37,5 @@
   assert_true(p1_resolved);
   assert_true(p2_resolved);
   assert_true(p3_resolved);
-}, "navigation.navigate() returns a finished promise that awaits all promises if event.transitionWhile() is called multiple times");
+}, "navigation.navigate() returns a finished promise that awaits all promises if event.intercept() is called multiple times");
 </script>
diff --git a/testing/web-platform/tests/navigation-api/navigate-event/transitionWhile-navigation-back.html b/testing/web-platform/tests/navigation-api/navigate-event/intercept-navigation-back.html
similarity index 80%
rename from testing/web-platform/tests/navigation-api/navigate-event/transitionWhile-navigation-back.html
rename to testing/web-platform/tests/navigation-api/navigate-event/intercept-navigation-back.html
index 3a4629005be58..8babf2bcdcc5b 100644
--- a/testing/web-platform/tests/navigation-api/navigate-event/transitionWhile-navigation-back.html
+++ b/testing/web-platform/tests/navigation-api/navigate-event/intercept-navigation-back.html
@@ -8,12 +8,12 @@
   window.onload = () => t.step_timeout(() => {
     navigation.navigate("#foo").committed.then(() => {
       assert_true(navigation.canGoBack);
-      navigation.onnavigate = t.step_func(e => e.transitionWhile(Promise.resolve()));
+      navigation.onnavigate = t.step_func(e => e.intercept());
       navigation.back().committed.then(t.step_func_done(() => {
         assert_equals(navigation.entries().length, 2);
         assert_equals(navigation.currentEntry, navigation.entries()[0]);
       }));
     });
   }, 0);
-}, "event.transitionWhile() can intercept navigation.back()");
+}, "event.intercept() can intercept navigation.back()");
 </script>
diff --git a/testing/web-platform/tests/navigation-api/navigate-event/transitionWhile-on-synthetic-event.html b/testing/web-platform/tests/navigation-api/navigate-event/intercept-on-synthetic-event.html
similarity index 74%
rename from testing/web-platform/tests/navigation-api/navigate-event/transitionWhile-on-synthetic-event.html
rename to testing/web-platform/tests/navigation-api/navigate-event/intercept-on-synthetic-event.html
index 3acf41745811a..3a4b54de5e9c9 100644
--- a/testing/web-platform/tests/navigation-api/navigate-event/transitionWhile-on-synthetic-event.html
+++ b/testing/web-platform/tests/navigation-api/navigate-event/intercept-on-synthetic-event.html
@@ -10,8 +10,8 @@
       signal: (new AbortController()).signal
     });
 
-    assert_throws_dom("SecurityError", () => event.transitionWhile(Promise.resolve()));
+    assert_throws_dom("SecurityError", () => event.intercept());
   });
   history.pushState(1, null, "#1");
-}, "event.transitionWhile() throws if invoked on a synthetic event");
+}, "event.intercept() throws if invoked on a synthetic event");
 </script>
diff --git a/testing/web-platform/tests/navigation-api/navigate-event/transitionWhile-popstate.html b/testing/web-platform/tests/navigation-api/navigate-event/intercept-popstate.html
similarity index 82%
rename from testing/web-platform/tests/navigation-api/navigate-event/transitionWhile-popstate.html
rename to testing/web-platform/tests/navigation-api/navigate-event/intercept-popstate.html
index a889e40e22b5a..f5f9d82be7f7e 100644
--- a/testing/web-platform/tests/navigation-api/navigate-event/transitionWhile-popstate.html
+++ b/testing/web-platform/tests/navigation-api/navigate-event/intercept-popstate.html
@@ -14,7 +14,7 @@
     onpopstate_fired = true;
     last_state = e.state;
   }
-  navigation.onnavigate = t.step_func(e => e.transitionWhile(Promise.resolve()));
+  navigation.onnavigate = t.step_func(e => e.intercept());
 
   await navigation.navigate("#").finished;
   assert_true(navigation.canGoBack);
@@ -22,5 +22,5 @@
   await navigation.back().finished;
   assert_true(onpopstate_fired);
   assert_not_equals(last_state, null);
-}, "event.transitionWhile() should provide popstate with a valid state object");
+}, "event.intercept() should provide popstate with a valid state object");
 </script>
diff --git a/testing/web-platform/tests/navigation-api/navigate-event/intercept-reject.html b/testing/web-platform/tests/navigation-api/navigate-event/intercept-reject.html
new file mode 100644
index 0000000000000..4c5ec0163d1ab
--- /dev/null
+++ b/testing/web-platform/tests/navigation-api/navigate-event/intercept-reject.html
@@ -0,0 +1,29 @@
+<!doctype html>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script>
+async_test(t => {
+  const err = new TypeError("a message");
+  let start_href = location.href;
+
+  navigation.onnavigatesuccess = t.step_func_done(assert_unreached);
+  navigation.onnavigateerror = t.step_func_done(e => {
+    assert_equals(location.hash, "#1");
+    assert_equals(e.constructor, ErrorEvent);
+    assert_true(e.error === err);
+    assert_equals(e.message, "Uncaught TypeError: a message");
+    assert_equals(e.filename, start_href);
+    assert_greater_than(e.colno, 0);
+    assert_greater_than(e.lineno, 0);
+  });
+  navigation.onnavigate = e => {
+    e.intercept({ handler: async () => {
+      await new Promise(r => t.step_timeout(r, 0));
+      return Promise.reject(err);
+    }});
+  };
+
+  location.href = "#1";
+  assert_equals(location.hash, "#1");
+}, "event.intercept() should abort if the given promise rejects");
+</script>
diff --git a/testing/web-platform/tests/navigation-api/navigate-event/transitionWhile-resolve.html b/testing/web-platform/tests/navigation-api/navigate-event/intercept-resolve.html
similarity index 77%
rename from testing/web-platform/tests/navigation-api/navigate-event/transitionWhile-resolve.html
rename to testing/web-platform/tests/navigation-api/navigate-event/intercept-resolve.html
index b49c66399daee..b60d89b5dfee2 100644
--- a/testing/web-platform/tests/navigation-api/navigate-event/transitionWhile-resolve.html
+++ b/testing/web-platform/tests/navigation-api/navigate-event/intercept-resolve.html
@@ -11,10 +11,10 @@
   });
   navigation.onnavigateerror = t.step_func_done(assert_unreached);
   navigation.onnavigate = e => {
-    e.transitionWhile(new Promise(resolve => t.step_timeout(resolve, 0)));
+    e.intercept({ handler: () => new Promise(resolve => t.step_timeout(resolve, 0)) });
   };
 
   location.href = "#1";
   assert_equals(location.hash, "#1");
-}, "event.transitionWhile() should proceed if the given promise resolves");
+}, "event.intercept() should proceed if the given promise resolves");
 </script>
diff --git a/testing/web-platform/tests/navigation-api/navigate-event/transitionWhile-same-document-history-back.html b/testing/web-platform/tests/navigation-api/navigate-event/intercept-same-document-history-back.html
similarity index 91%
rename from testing/web-platform/tests/navigation-api/navigate-event/transitionWhile-same-document-history-back.html
rename to testing/web-platform/tests/navigation-api/navigate-event/intercept-same-document-history-back.html
index 4c404386fe216..6faabe1964651 100644
--- a/testing/web-platform/tests/navigation-api/navigate-event/transitionWhile-same-document-history-back.html
+++ b/testing/web-platform/tests/navigation-api/navigate-event/intercept-same-document-history-back.html
@@ -10,7 +10,7 @@
     let onnavigatesuccess_calls = 0;
     navigation.onnavigate = e => {
       onnavigate_calls++;
-      e.transitionWhile(Promise.resolve());
+      e.intercept();
     }
     navigation.onnavigatesuccess = t.step_func(e => {
       onnavigatesuccess_calls++;
@@ -36,5 +36,5 @@
         history.back();
       }));
   }, 0);
-}, "event.transitionWhile() can intercept same-document history.back()");
+}, "event.intercept() can intercept same-document history.back()");
 </script>
diff --git a/testing/web-platform/tests/navigation-api/navigate-event/navigate-anchor-cross-origin.html b/testing/web-platform/tests/navigation-api/navigate-event/navigate-anchor-cross-origin.html
index 38b7d584b8856..d8f2e383124be 100644
--- a/testing/web-platform/tests/navigation-api/navigate-event/navigate-anchor-cross-origin.html
+++ b/testing/web-platform/tests/navigation-api/navigate-event/navigate-anchor-cross-origin.html
@@ -7,7 +7,7 @@
   navigation.onnavigate = t.step_func_done(e => {
     assert_equals(e.navigationType, "push");
     assert_true(e.cancelable);
-    assert_false(e.canTransition);
+    assert_false(e.canIntercept);
     assert_false(e.userInitiated);
     assert_false(e.hashChange);
     assert_equals(e.formData, null);
diff --git a/testing/web-platform/tests/navigation-api/navigate-event/navigate-anchor-download-userInitiated.html b/testing/web-platform/tests/navigation-api/navigate-event/navigate-anchor-download-userInitiated.html
index c42f389ba67be..90a612b758869 100644
--- a/testing/web-platform/tests/navigation-api/navigate-event/navigate-anchor-download-userInitiated.html
+++ b/testing/web-platform/tests/navigation-api/navigate-event/navigate-anchor-download-userInitiated.html
@@ -11,7 +11,7 @@
   navigation.onnavigate = t.step_func(e => {
     assert_equals(e.navigationType, "push");
     assert_true(e.cancelable);
-    assert_true(e.canTransition);
+    assert_true(e.canIntercept);
     assert_true(e.userInitiated);
     assert_false(e.hashChange);
     assert_equals(e.downloadRequest, "");
diff --git a/testing/web-platform/tests/navigation-api/navigate-event/navigate-anchor-download.html b/testing/web-platform/tests/navigation-api/navigate-event/navigate-anchor-download.html
index 5615e34738445..c5ca306b7908d 100644
--- a/testing/web-platform/tests/navigation-api/navigate-event/navigate-anchor-download.html
+++ b/testing/web-platform/tests/navigation-api/navigate-event/navigate-anchor-download.html
@@ -14,7 +14,7 @@
     navigation.onnavigate = t.step_func_done(e => {
       assert_equals(e.navigationType, "push");
       assert_true(e.cancelable);
-      assert_true(e.canTransition);
+      assert_true(e.canIntercept);
       assert_false(e.userInitiated);
       assert_false(e.hashChange);
       assert_equals(e.downloadRequest, download_attr);
diff --git a/testing/web-platform/tests/navigation-api/navigate-event/navigate-anchor-fragment.html b/testing/web-platform/tests/navigation-api/navigate-event/navigate-anchor-fragment.html
index 591ed73dbf164..b7706b7debea3 100644
--- a/testing/web-platform/tests/navigation-api/navigate-event/navigate-anchor-fragment.html
+++ b/testing/web-platform/tests/navigation-api/navigate-event/navigate-anchor-fragment.html
@@ -7,7 +7,7 @@
   navigation.onnavigate = t.step_func(e => {
     assert_equals(e.navigationType, "push");
     assert_true(e.cancelable);
-    assert_true(e.canTransition);
+    assert_true(e.canIntercept);
     assert_false(e.userInitiated);
     assert_true(e.hashChange);
     assert_equals(e.downloadRequest, null);
diff --git a/testing/web-platform/tests/navigation-api/navigate-event/navigate-anchor-same-origin-cross-document.html b/testing/web-platform/tests/navigation-api/navigate-event/navigate-anchor-same-origin-cross-document.html
index 822f2f33ba4df..b8e925a4dbacd 100644
--- a/testing/web-platform/tests/navigation-api/navigate-event/navigate-anchor-same-origin-cross-document.html
+++ b/testing/web-platform/tests/navigation-api/navigate-event/navigate-anchor-same-origin-cross-document.html
@@ -7,7 +7,7 @@
   navigation.onnavigate = t.step_func_done(e => {
     assert_equals(e.navigationType, "push");
     assert_true(e.cancelable);
-    assert_true(e.canTransition);
+    assert_true(e.canIntercept);
     assert_false(e.userInitiated);
     assert_false(e.hashChange);
     assert_equals(e.formData, null);
diff --git a/testing/web-platform/tests/navigation-api/navigate-event/navigate-anchor-userInitiated.html b/testing/web-platform/tests/navigation-api/navigate-event/navigate-anchor-userInitiated.html
index 832a3f843e22f..b746bbe3f028c 100644
--- a/testing/web-platform/tests/navigation-api/navigate-event/navigate-anchor-userInitiated.html
+++ b/testing/web-platform/tests/navigation-api/navigate-event/navigate-anchor-userInitiated.html
@@ -10,7 +10,7 @@
   navigation.onnavigate = t.step_func(e => {
     assert_equals(e.navigationType, "push");
     assert_true(e.cancelable);
-    assert_true(e.canTransition);
+    assert_true(e.canIntercept);
     assert_true(e.userInitiated);
     assert_true(e.hashChange);
     assert_equals(e.formData, null);
diff --git a/testing/web-platform/tests/navigation-api/navigate-event/navigate-anchor-with-target.html b/testing/web-platform/tests/navigation-api/navigate-event/navigate-anchor-with-target.html
index a0de04d5ea442..c2053a37b09a4 100644
--- a/testing/web-platform/tests/navigation-api/navigate-event/navigate-anchor-with-target.html
+++ b/testing/web-platform/tests/navigation-api/navigate-event/navigate-anchor-with-target.html
@@ -12,7 +12,7 @@
     iframe.contentWindow.navigation.onnavigate = t.step_func_done(e => {
       assert_equals(e.navigationType, "push");
       assert_true(e.cancelable);
-      assert_true(e.canTransition);
+      assert_true(e.canIntercept);
       assert_false(e.userInitiated);
       assert_false(e.hashChange);
       assert_equals(e.formData, null);
diff --git a/testing/web-platform/tests/navigation-api/navigate-event/navigate-form-get.html b/testing/web-platform/tests/navigation-api/navigate-event/navigate-form-get.html
index d3cafa1b3fa34..69a49eb08a677 100644
--- a/testing/web-platform/tests/navigation-api/navigate-event/navigate-form-get.html
+++ b/testing/web-platform/tests/navigation-api/navigate-event/navigate-form-get.html
@@ -9,7 +9,7 @@
 
     assert_equals(e.navigationType, "replace");
     assert_true(e.cancelable);
-    assert_true(e.canTransition);
+    assert_true(e.canIntercept);
     assert_false(e.userInitiated);
     assert_false(e.hashChange);
     assert_equals(e.downloadRequest, null);
diff --git a/testing/web-platform/tests/navigation-api/navigate-event/navigate-form-userInitiated.html b/testing/web-platform/tests/navigation-api/navigate-event/navigate-form-userInitiated.html
index d6fc712c26a09..454f0773962f3 100644
--- a/testing/web-platform/tests/navigation-api/navigate-event/navigate-form-userInitiated.html
+++ b/testing/web-platform/tests/navigation-api/navigate-event/navigate-form-userInitiated.html
@@ -14,7 +14,7 @@
 
     assert_equals(e.navigationType, "push");
     assert_true(e.cancelable);
-    assert_true(e.canTransition);
+    assert_true(e.canIntercept);
     assert_true(e.userInitiated);
     assert_false(e.hashChange);
     assert_equals(e.downloadRequest, null);
diff --git a/testing/web-platform/tests/navigation-api/navigate-event/navigate-form-with-target.html b/testing/web-platform/tests/navigation-api/navigate-event/navigate-form-with-target.html
index 12cafe5eb0815..b23ab3a70ccb2 100644
--- a/testing/web-platform/tests/navigation-api/navigate-event/navigate-form-with-target.html
+++ b/testing/web-platform/tests/navigation-api/navigate-event/navigate-form-with-target.html
@@ -11,7 +11,7 @@
     iframe.contentWindow.navigation.onnavigate = t.step_func_done(e => {
       assert_equals(e.navigationType, "push");
       assert_true(e.cancelable);
-      assert_true(e.canTransition);
+      assert_true(e.canIntercept);
       assert_false(e.userInitiated);
       assert_false(e.hashChange);
       assert_equals(e.downloadRequest, null);
diff --git a/testing/web-platform/tests/navigation-api/navigate-event/navigate-form.html b/testing/web-platform/tests/navigation-api/navigate-event/navigate-form.html
index bc120420ca3c1..b537a9b58f090 100644
--- a/testing/web-platform/tests/navigation-api/navigate-event/navigate-form.html
+++ b/testing/web-platform/tests/navigation-api/navigate-event/navigate-form.html
@@ -9,7 +9,7 @@
 
     assert_equals(e.navigationType, "replace");
     assert_true(e.cancelable);
-    assert_true(e.canTransition);
+    assert_true(e.canIntercept);
     assert_false(e.userInitiated);
     assert_false(e.hashChange);
     assert_equals(e.downloadRequest, null);
diff --git a/testing/web-platform/tests/navigation-api/navigate-event/navigate-history-back-after-fragment.html b/testing/web-platform/tests/navigation-api/navigate-event/navigate-history-back-after-fragment.html
index ddabfaeef5afc..976754f28a885 100644
--- a/testing/web-platform/tests/navigation-api/navigate-event/navigate-history-back-after-fragment.html
+++ b/testing/web-platform/tests/navigation-api/navigate-event/navigate-history-back-after-fragment.html
@@ -13,7 +13,7 @@
     navigation.onnavigate = t.step_func_done(e => {
       assert_equals(e.navigationType, "traverse");
       assert_false(e.cancelable);
-      assert_true(e.canTransition);
+      assert_true(e.canIntercept);
       assert_false(e.userInitiated);
       assert_true(e.hashChange);
       assert_equals(e.downloadRequest, null);
diff --git a/testing/web-platform/tests/navigation-api/navigate-event/navigate-history-back-after-pushState.html b/testing/web-platform/tests/navigation-api/navigate-event/navigate-history-back-after-pushState.html
index 074aa71568159..4d870fb2ae6d0 100644
--- a/testing/web-platform/tests/navigation-api/navigate-event/navigate-history-back-after-pushState.html
+++ b/testing/web-platform/tests/navigation-api/navigate-event/navigate-history-back-after-pushState.html
@@ -13,7 +13,7 @@
     navigation.onnavigate = t.step_func_done(e => {
       assert_equals(e.navigationType, "traverse");
       assert_false(e.cancelable);
-      assert_true(e.canTransition);
+      assert_true(e.canIntercept);
       assert_false(e.userInitiated);
       assert_false(e.hashChange);
       assert_equals(e.downloadRequest, null);
diff --git a/testing/web-platform/tests/navigation-api/navigate-event/navigate-history-back-cross-document.html b/testing/web-platform/tests/navigation-api/navigate-event/navigate-history-back-cross-document.html
index 967cf5db0cdb4..cd7be6e9ad37e 100644
--- a/testing/web-platform/tests/navigation-api/navigate-event/navigate-history-back-cross-document.html
+++ b/testing/web-platform/tests/navigation-api/navigate-event/navigate-history-back-cross-document.html
@@ -12,7 +12,7 @@
       i.contentWindow.navigation.onnavigate = t.step_func_done(e => {
         assert_equals(e.navigationType, "traverse");
         assert_false(e.cancelable);
-        assert_false(e.canTransition);
+        assert_false(e.canIntercept);
         assert_false(e.userInitiated);
         assert_false(e.hashChange);
         assert_equals(e.downloadRequest, null);
diff --git a/testing/web-platform/tests/navigation-api/navigate-event/navigate-history-go-0.html b/testing/web-platform/tests/navigation-api/navigate-event/navigate-history-go-0.html
index f7453e4805f8c..96d98cf44c826 100644
--- a/testing/web-platform/tests/navigation-api/navigate-event/navigate-history-go-0.html
+++ b/testing/web-platform/tests/navigation-api/navigate-event/navigate-history-go-0.html
@@ -8,7 +8,7 @@
     i.contentWindow.navigation.onnavigate = t.step_func_done(e => {
       assert_equals(e.navigationType, "reload");
       assert_true(e.cancelable);
-      assert_true(e.canTransition);
+      assert_true(e.canIntercept);
       assert_false(e.userInitiated);
       assert_false(e.hashChange);
       assert_equals(e.downloadRequest, null);
diff --git a/testing/web-platform/tests/navigation-api/navigate-event/navigate-history-pushState.html b/testing/web-platform/tests/navigation-api/navigate-event/navigate-history-pushState.html
index 0651c529daa3e..2f8c81c7090cb 100644
--- a/testing/web-platform/tests/navigation-api/navigate-event/navigate-history-pushState.html
+++ b/testing/web-platform/tests/navigation-api/navigate-event/navigate-history-pushState.html
@@ -7,7 +7,7 @@
   navigation.onnavigate = t.step_func(e => {
     assert_equals(e.navigationType, "push");
     assert_true(e.cancelable);
-    assert_true(e.canTransition);
+    assert_true(e.canIntercept);
     assert_false(e.userInitiated);
     assert_false(e.hashChange);
     assert_equals(e.downloadRequest, null);
diff --git a/testing/web-platform/tests/navigation-api/navigate-event/navigate-history-replaceState.html b/testing/web-platform/tests/navigation-api/navigate-event/navigate-history-replaceState.html
index d0fe5d949ba17..d8417fbfd308a 100644
--- a/testing/web-platform/tests/navigation-api/navigate-event/navigate-history-replaceState.html
+++ b/testing/web-platform/tests/navigation-api/navigate-event/navigate-history-replaceState.html
@@ -7,7 +7,7 @@
   navigation.onnavigate = t.step_func(e => {
     assert_equals(e.navigationType, "replace");
     assert_true(e.cancelable);
-    assert_true(e.canTransition);
+    assert_true(e.canIntercept);
     assert_false(e.userInitiated);
     assert_false(e.hashChange);
     assert_equals(e.downloadRequest, null);
diff --git a/testing/web-platform/tests/navigation-api/navigate-event/navigate-iframe-location.html b/testing/web-platform/tests/navigation-api/navigate-event/navigate-iframe-location.html
index cbf16c896a856..059b995011836 100644
--- a/testing/web-platform/tests/navigation-api/navigate-event/navigate-iframe-location.html
+++ b/testing/web-platform/tests/navigation-api/navigate-event/navigate-iframe-location.html
@@ -11,7 +11,7 @@
     iframe.contentWindow.navigation.onnavigate = t.step_func_done(e => {
       assert_equals(e.navigationType, "push");
       assert_true(e.cancelable);
-      assert_true(e.canTransition);
+      assert_true(e.canIntercept);
       assert_false(e.userInitiated);
       assert_true(e.hashChange);
       assert_equals(e.downloadRequest, null);
diff --git a/testing/web-platform/tests/navigation-api/navigate-event/navigate-location.html b/testing/web-platform/tests/navigation-api/navigate-event/navigate-location.html
index 998da50994cae..c5aa0be97a47b 100644
--- a/testing/web-platform/tests/navigation-api/navigate-event/navigate-location.html
+++ b/testing/web-platform/tests/navigation-api/navigate-event/navigate-location.html
@@ -7,7 +7,7 @@
   navigation.onnavigate = t.step_func_done(e => {
     assert_equals(e.navigationType, "replace");
     assert_true(e.cancelable);
-    assert_true(e.canTransition);
+    assert_true(e.canIntercept);
     assert_false(e.userInitiated);
     assert_true(e.hashChange);
     assert_equals(e.downloadRequest, null);
diff --git a/testing/web-platform/tests/navigation-api/navigate-event/navigate-meta-refresh.html b/testing/web-platform/tests/navigation-api/navigate-event/navigate-meta-refresh.html
index 9077fec5fa053..1f8ed306851fd 100644
--- a/testing/web-platform/tests/navigation-api/navigate-event/navigate-meta-refresh.html
+++ b/testing/web-platform/tests/navigation-api/navigate-event/navigate-meta-refresh.html
@@ -10,7 +10,7 @@
     i.contentWindow.navigation.onnavigate = t.step_func_done(e => {
       assert_equals(e.navigationType, "reload");
       assert_true(e.cancelable);
-      assert_true(e.canTransition);
+      assert_true(e.canIntercept);
       assert_false(e.userInitiated);
       assert_false(e.hashChange);
       assert_equals(e.downloadRequest, null);
diff --git a/testing/web-platform/tests/navigation-api/navigate-event/navigate-navigation-back-cross-document.html b/testing/web-platform/tests/navigation-api/navigate-event/navigate-navigation-back-cross-document.html
index 4847ac8f1be90..214644066e1d1 100644
--- a/testing/web-platform/tests/navigation-api/navigate-event/navigate-navigation-back-cross-document.html
+++ b/testing/web-platform/tests/navigation-api/navigate-event/navigate-navigation-back-cross-document.html
@@ -12,7 +12,7 @@
       i.contentWindow.navigation.onnavigate = t.step_func_done(e => {
         assert_equals(e.navigationType, "traverse");
         assert_false(e.cancelable);
-        assert_false(e.canTransition);
+        assert_false(e.canIntercept);
         assert_false(e.userInitiated);
         assert_false(e.hashChange);
         assert_equals(e.downloadRequest, null);
diff --git a/testing/web-platform/tests/navigation-api/navigate-event/navigate-navigation-back-same-document.html b/testing/web-platform/tests/navigation-api/navigate-event/navigate-navigation-back-same-document.html
index 626ea33136adb..8753e6b1c86ba 100644
--- a/testing/web-platform/tests/navigation-api/navigate-event/navigate-navigation-back-same-document.html
+++ b/testing/web-platform/tests/navigation-api/navigate-event/navigate-navigation-back-same-document.html
@@ -12,7 +12,7 @@
       navigation.onnavigate = t.step_func_done(e => {
         assert_equals(e.navigationType, "traverse");
         assert_false(e.cancelable);
-        assert_true(e.canTransition);
+        assert_true(e.canIntercept);
         assert_false(e.userInitiated);
         assert_true(e.hashChange);
         assert_equals(e.downloadRequest, null);
diff --git a/testing/web-platform/tests/navigation-api/navigate-event/navigate-navigation-navigate.html b/testing/web-platform/tests/navigation-api/navigate-event/navigate-navigation-navigate.html
index adc71a324379a..76f98c7236106 100644
--- a/testing/web-platform/tests/navigation-api/navigate-event/navigate-navigation-navigate.html
+++ b/testing/web-platform/tests/navigation-api/navigate-event/navigate-navigation-navigate.html
@@ -6,7 +6,7 @@
   navigation.onnavigate = t.step_func_done(e => {
     assert_equals(e.navigationType, "replace");
     assert_true(e.cancelable);
-    assert_true(e.canTransition);
+    assert_true(e.canIntercept);
     assert_false(e.userInitiated);
     assert_true(e.hashChange);
     assert_equals(e.downloadRequest, null);
diff --git a/testing/web-platform/tests/navigation-api/navigate-event/navigate-to-srcdoc.html b/testing/web-platform/tests/navigation-api/navigate-event/navigate-to-srcdoc.html
index 996fecfceaf67..26ad135b6ad0b 100644
--- a/testing/web-platform/tests/navigation-api/navigate-event/navigate-to-srcdoc.html
+++ b/testing/web-platform/tests/navigation-api/navigate-event/navigate-to-srcdoc.html
@@ -11,7 +11,7 @@
     iframe.contentWindow.navigation.onnavigate = t.step_func(e => {
       assert_equals(e.navigationType, "push");
       assert_true(e.cancelable, "cancelable");
-      assert_false(e.canTransition, "canTransition");
+      assert_false(e.canIntercept, "canIntercept");
       assert_false(e.userInitiated, "userInitiated");
       assert_false(e.hashChange, "hashChange");
       assert_equals(e.downloadRequest, null);
diff --git a/testing/web-platform/tests/navigation-api/navigate-event/navigate-window-open-self.html b/testing/web-platform/tests/navigation-api/navigate-event/navigate-window-open-self.html
index cdfc57c4a022f..274c8bc4d5762 100644
--- a/testing/web-platform/tests/navigation-api/navigate-event/navigate-window-open-self.html
+++ b/testing/web-platform/tests/navigation-api/navigate-event/navigate-window-open-self.html
@@ -6,7 +6,7 @@
   navigation.onnavigate = t.step_func_done(e => {
     assert_equals(e.navigationType, "push");
     assert_true(e.cancelable);
-    assert_true(e.canTransition);
+    assert_true(e.canIntercept);
     assert_false(e.userInitiated);
     assert_true(e.hashChange);
     assert_equals(e.downloadRequest, null);
diff --git a/testing/web-platform/tests/navigation-api/navigate-event/navigate-window-open.html b/testing/web-platform/tests/navigation-api/navigate-event/navigate-window-open.html
index aef333abc4d19..afc998271f6e9 100644
--- a/testing/web-platform/tests/navigation-api/navigate-event/navigate-window-open.html
+++ b/testing/web-platform/tests/navigation-api/navigate-event/navigate-window-open.html
@@ -11,7 +11,7 @@
     iframe.contentWindow.navigation.onnavigate = t.step_func_done(e => {
       assert_equals(e.navigationType, "push");
       assert_true(e.cancelable);
-      assert_true(e.canTransition);
+      assert_true(e.canIntercept);
       assert_false(e.userInitiated);
       assert_true(e.hashChange);
       assert_equals(e.downloadRequest, null);
diff --git a/testing/web-platform/tests/navigation-api/navigate-event/signal-abort-transitionWhile.html b/testing/web-platform/tests/navigation-api/navigate-event/signal-abort-intercept.html
similarity index 82%
rename from testing/web-platform/tests/navigation-api/navigate-event/signal-abort-transitionWhile.html
rename to testing/web-platform/tests/navigation-api/navigate-event/signal-abort-intercept.html
index ce195cf677229..1e92d8e445f6c 100644
--- a/testing/web-platform/tests/navigation-api/navigate-event/signal-abort-transitionWhile.html
+++ b/testing/web-platform/tests/navigation-api/navigate-event/signal-abort-intercept.html
@@ -8,11 +8,11 @@
   navigation.onnavigate = t.step_func(e => {
     abort_signal = e.signal;
     abort_signal.onabort = () => onabort_called = true;
-    e.transitionWhile(Promise.resolve());
+    e.intercept();
   });
 
   await navigation.navigate("?1").finished;
   assert_false(abort_signal.aborted);
   assert_false(onabort_called);
-}, "event.transitionWhile() does not signal event.signal");
+}, "event.intercept() does not signal event.signal");
 </script>
diff --git a/testing/web-platform/tests/navigation-api/navigate-event/signal-abort-window-stop-after-transitionWhile.html b/testing/web-platform/tests/navigation-api/navigate-event/signal-abort-window-stop-after-intercept.html
similarity index 88%
rename from testing/web-platform/tests/navigation-api/navigate-event/signal-abort-window-stop-after-transitionWhile.html
rename to testing/web-platform/tests/navigation-api/navigate-event/signal-abort-window-stop-after-intercept.html
index bc44a07b20e83..51ba7753a8a9f 100644
--- a/testing/web-platform/tests/navigation-api/navigate-event/signal-abort-window-stop-after-transitionWhile.html
+++ b/testing/web-platform/tests/navigation-api/navigate-event/signal-abort-window-stop-after-intercept.html
@@ -19,7 +19,7 @@
     navigation.onnavigate = t.step_func(e => {
       abort_signal = e.signal;
       abort_signal.onabort = () => onabort_called = true;
-      e.transitionWhile(new Promise(resolve => t.step_timeout(resolve, 0)));
+      e.intercept({ handler: () => new Promise(resolve => t.step_timeout(resolve, 0)) });
     });
     let result = navigation.navigate("?1");
     window.stop();
@@ -36,5 +36,5 @@
       t.step_timeout(t.step_func_done(() => {}), 5);
     });
   });
-}, "window.stop() cancels the navigate event's transitionWhile() and signals event.signal");
+}, "window.stop() cancels the navigate event's intercept() and signals event.signal");
 </script>
diff --git a/testing/web-platform/tests/navigation-api/navigation-history-entry/key-id-location-reload-transitionWhile.html b/testing/web-platform/tests/navigation-api/navigation-history-entry/key-id-location-reload-intercept.html
similarity index 91%
rename from testing/web-platform/tests/navigation-api/navigation-history-entry/key-id-location-reload-transitionWhile.html
rename to testing/web-platform/tests/navigation-api/navigation-history-entry/key-id-location-reload-intercept.html
index e5924d243160c..62ce0974399e8 100644
--- a/testing/web-platform/tests/navigation-api/navigation-history-entry/key-id-location-reload-transitionWhile.html
+++ b/testing/web-platform/tests/navigation-api/navigation-history-entry/key-id-location-reload-intercept.html
@@ -10,7 +10,7 @@
   const original = i.contentWindow.navigation.currentEntry;
   const { key, id } = original;
 
-  i.contentWindow.navigation.addEventListener("navigate", e => e.transitionWhile(Promise.resolve()));
+  i.contentWindow.navigation.addEventListener("navigate", e => e.intercept());
 
   i.onload = t.unreached_func("the iframe must not reload");
 
@@ -19,5 +19,5 @@
   assert_equals(i.contentWindow.navigation.currentEntry, original);
   assert_equals(i.contentWindow.navigation.currentEntry.key, key);
   assert_equals(i.contentWindow.navigation.currentEntry.id, id);
-}, "NavigationHistoryEntry's key and id after location.reload() intercepted by transitionWhile()");
+}, "NavigationHistoryEntry's key and id after location.reload() intercepted by intercept()");
 </script>
diff --git a/testing/web-platform/tests/navigation-api/navigation-methods/navigate-transitionWhile-history-state.html b/testing/web-platform/tests/navigation-api/navigation-methods/navigate-intercept-history-state.html
similarity index 70%
rename from testing/web-platform/tests/navigation-api/navigation-methods/navigate-transitionWhile-history-state.html
rename to testing/web-platform/tests/navigation-api/navigation-methods/navigate-intercept-history-state.html
index c5e1036bff4fc..7faf6ffb5a294 100644
--- a/testing/web-platform/tests/navigation-api/navigation-methods/navigate-transitionWhile-history-state.html
+++ b/testing/web-platform/tests/navigation-api/navigation-methods/navigate-intercept-history-state.html
@@ -6,9 +6,9 @@
   history.replaceState("state1", "", "#1");
   assert_equals(history.state, "state1");
 
-  navigation.onnavigate = e => e.transitionWhile(Promise.resolve("r"));
+  navigation.onnavigate = e => e.intercept({ handler: () => Promise.resolve("r") });
   await navigation.navigate("#2").committed;
   assert_equals(location.hash, "#2");
   assert_equals(history.state, null);
-}, "history.story should be nulled by navigate() handled by transitionWhile()");
+}, "history.story should be nulled by navigate() handled by intercept()");
 </script>
diff --git a/testing/web-platform/tests/navigation-api/navigation-methods/navigate-state-repeated-await.html b/testing/web-platform/tests/navigation-api/navigation-methods/navigate-state-repeated-await.html
index a003992d66a3b..539b3dc1da9de 100644
--- a/testing/web-platform/tests/navigation-api/navigation-methods/navigate-state-repeated-await.html
+++ b/testing/web-platform/tests/navigation-api/navigation-methods/navigate-state-repeated-await.html
@@ -3,7 +3,7 @@
 <script src="/resources/testharnessreport.js"></script>
 <script>
 promise_test(async t => {
-  navigation.onnavigate = e => e.transitionWhile(Promise.resolve());
+  navigation.onnavigate = e => e.intercept();
 
   await navigation.navigate('/foo', {state: {foo: 1}}).committed;
   assert_equals(navigation.currentEntry.getState().foo, 1);
diff --git a/testing/web-platform/tests/navigation-api/navigation-methods/navigate-state-repeated.html b/testing/web-platform/tests/navigation-api/navigation-methods/navigate-state-repeated.html
index 29c3f68eeb0ca..227bbb0cfcce4 100644
--- a/testing/web-platform/tests/navigation-api/navigation-methods/navigate-state-repeated.html
+++ b/testing/web-platform/tests/navigation-api/navigation-methods/navigate-state-repeated.html
@@ -3,7 +3,7 @@
 <script src="/resources/testharnessreport.js"></script>
 <script>
 promise_test(async t => {
-  navigation.onnavigate = e => e.transitionWhile(Promise.resolve());
+  navigation.onnavigate = e => e.intercept();
 
   let result1 = navigation.navigate('/foo', {state: {foo: 1}});
   assert_equals(navigation.currentEntry.getState().foo, 1);
diff --git a/testing/web-platform/tests/navigation-api/navigation-methods/reload-state-and-info.html b/testing/web-platform/tests/navigation-api/navigation-methods/reload-state-and-info.html
index a68dd2ab8be01..1ba26ae3da4b2 100644
--- a/testing/web-platform/tests/navigation-api/navigation-methods/reload-state-and-info.html
+++ b/testing/web-platform/tests/navigation-api/navigation-methods/reload-state-and-info.html
@@ -19,7 +19,7 @@
       let onnavigate_called = false;
       let promise_settled = false;
       i.contentWindow.navigation.onnavigate = t.step_func(e => {
-        e.transitionWhile(Promise.resolve());
+        e.intercept();
         onnavigate_called = true;
         assert_equals(e.info, navInfo);
         assert_equals(e.navigationType, "reload");
diff --git a/testing/web-platform/tests/navigation-api/navigation-methods/reload-state-undefined.html b/testing/web-platform/tests/navigation-api/navigation-methods/reload-state-undefined.html
index ac204d4731b5d..b8b34650abf9f 100644
--- a/testing/web-platform/tests/navigation-api/navigation-methods/reload-state-undefined.html
+++ b/testing/web-platform/tests/navigation-api/navigation-methods/reload-state-undefined.html
@@ -18,7 +18,7 @@
       let onnavigate_called = false;
       let promise_settled = false;
       i.contentWindow.navigation.onnavigate = t.step_func(e => {
-        e.transitionWhile(Promise.resolve());
+        e.intercept();
         onnavigate_called = true;
         assert_equals(e.info, navInfo);
         assert_equals(e.navigationType, "reload");
diff --git a/testing/web-platform/tests/navigation-api/navigation-methods/return-value/back-transitionWhile-rejected.html b/testing/web-platform/tests/navigation-api/navigation-methods/return-value/back-intercept-rejected.html
similarity index 87%
rename from testing/web-platform/tests/navigation-api/navigation-methods/return-value/back-transitionWhile-rejected.html
rename to testing/web-platform/tests/navigation-api/navigation-methods/return-value/back-intercept-rejected.html
index fc171af54b986..9d4238087ff50 100644
--- a/testing/web-platform/tests/navigation-api/navigation-methods/return-value/back-transitionWhile-rejected.html
+++ b/testing/web-platform/tests/navigation-api/navigation-methods/return-value/back-intercept-rejected.html
@@ -19,10 +19,10 @@
   const err = new Error("boo!");
   const promise = Promise.reject(err);
   promise.catch(() => {}); // prevent unhandled rejection testharness.js errors
-  navigation.onnavigate = e => e.transitionWhile(promise);
+  navigation.onnavigate = e => e.intercept({ handler: () => promise });
 
   const result = navigation.back();
   await assertCommittedFulfillsFinishedRejectsExactly(t, result, entry0, err);
   assert_equals(navigation.currentEntry, entry0);
-}, "back() promise rejection with rejected transitionWhile()");
+}, "back() promise rejection with rejected intercept()");
 </script>
diff --git a/testing/web-platform/tests/navigation-api/navigation-methods/return-value/back-transitionWhile.html b/testing/web-platform/tests/navigation-api/navigation-methods/return-value/back-intercept.html
similarity index 83%
rename from testing/web-platform/tests/navigation-api/navigation-methods/return-value/back-transitionWhile.html
rename to testing/web-platform/tests/navigation-api/navigation-methods/return-value/back-intercept.html
index c1161f895a54d..2654045c2b008 100644
--- a/testing/web-platform/tests/navigation-api/navigation-methods/return-value/back-transitionWhile.html
+++ b/testing/web-platform/tests/navigation-api/navigation-methods/return-value/back-intercept.html
@@ -16,10 +16,10 @@
   assert_equals((new URL(entry0.url)).hash, "");
   assert_equals((new URL(entry1.url)).hash, "#1");
 
-  navigation.onnavigate = e => e.transitionWhile(Promise.resolve({ abc: "def" }));
+  navigation.onnavigate = e => e.intercept({ handler: () => Promise.resolve({ abc: "def" }) });
 
   const result = navigation.back();
   await assertBothFulfill(t, result, entry0);
   assert_equals(navigation.currentEntry, entry0);
-}, "back() and transitionWhile() with a fulfilled promise");
+}, "back() and intercept() with a fulfilled promise");
 </script>
diff --git a/testing/web-platform/tests/navigation-api/navigation-methods/return-value/forward-transitionWhile-rejected.html b/testing/web-platform/tests/navigation-api/navigation-methods/return-value/forward-intercept-rejected.html
similarity index 88%
rename from testing/web-platform/tests/navigation-api/navigation-methods/return-value/forward-transitionWhile-rejected.html
rename to testing/web-platform/tests/navigation-api/navigation-methods/return-value/forward-intercept-rejected.html
index 7ff0c70f0b9ae..9e86dcca19760 100644
--- a/testing/web-platform/tests/navigation-api/navigation-methods/return-value/forward-transitionWhile-rejected.html
+++ b/testing/web-platform/tests/navigation-api/navigation-methods/return-value/forward-intercept-rejected.html
@@ -20,10 +20,10 @@
   const err = new Error("boo!");
   const promise = Promise.reject(err);
   promise.catch(() => {}); // prevent unhandled rejection testharness.js errors
-  navigation.onnavigate = e => e.transitionWhile(promise);
+  navigation.onnavigate = e => e.intercept({ handler: () => promise });
 
   const result = navigation.forward();
   await assertCommittedFulfillsFinishedRejectsExactly(t, result, entry1, err);
   assert_equals(navigation.currentEntry, entry1);
-}, "forward() promise rejection with rejected transitionWhile()");
+}, "forward() promise rejection with rejected intercept()");
 </script>
diff --git a/testing/web-platform/tests/navigation-api/navigation-methods/return-value/forward-transitionWhile.html b/testing/web-platform/tests/navigation-api/navigation-methods/return-value/forward-intercept.html
similarity index 86%
rename from testing/web-platform/tests/navigation-api/navigation-methods/return-value/forward-transitionWhile.html
rename to testing/web-platform/tests/navigation-api/navigation-methods/return-value/forward-intercept.html
index 2b8175b619d61..ce4ab3217070a 100644
--- a/testing/web-platform/tests/navigation-api/navigation-methods/return-value/forward-transitionWhile.html
+++ b/testing/web-platform/tests/navigation-api/navigation-methods/return-value/forward-intercept.html
@@ -19,10 +19,10 @@
   await navigation.back().committed;
 
   const promise = Promise.resolve({ abc: "def" });
-  navigation.onnavigate = e => e.transitionWhile(promise);
+  navigation.onnavigate = e => e.intercept({ handler: () => promise });
 
   const result = navigation.forward();
   await assertBothFulfill(t, result, entry1);
   assert_equals(navigation.currentEntry, entry1);
-}, "forward() and transitionWhile() with a fulfilled promise");
+}, "forward() and intercept() with a fulfilled promise");
 </script>
diff --git a/testing/web-platform/tests/navigation-api/navigation-methods/return-value/navigate-transitionWhile-interrupted.html b/testing/web-platform/tests/navigation-api/navigation-methods/return-value/navigate-intercept-interrupted.html
similarity index 84%
rename from testing/web-platform/tests/navigation-api/navigation-methods/return-value/navigate-transitionWhile-interrupted.html
rename to testing/web-platform/tests/navigation-api/navigation-methods/return-value/navigate-intercept-interrupted.html
index fa818b484d327..36403c892c6c9 100644
--- a/testing/web-platform/tests/navigation-api/navigation-methods/return-value/navigate-transitionWhile-interrupted.html
+++ b/testing/web-platform/tests/navigation-api/navigation-methods/return-value/navigate-intercept-interrupted.html
@@ -9,7 +9,7 @@
   // into a replace navigation.
   await new Promise(resolve => window.onload = () => t.step_timeout(resolve, 0));
 
-  navigation.addEventListener("navigate", e => e.transitionWhile(Promise.resolve()));
+  navigation.addEventListener("navigate", e => e.intercept());
 
   const result1 = navigation.navigate("#1");
   const result2 = navigation.navigate("#2");
@@ -19,5 +19,5 @@
 
   await assertCommittedFulfillsFinishedRejectsDOM(t, result1, navigation.entries()[1], "AbortError");
   await assertBothFulfill(t, result2, navigation.currentEntry);
-}, "interrupted navigate() promises with transitionWhile()");
+}, "interrupted navigate() promises with intercept()");
 </script>
diff --git a/testing/web-platform/tests/navigation-api/navigation-methods/return-value/navigate-transitionWhile-rejected.html b/testing/web-platform/tests/navigation-api/navigation-methods/return-value/navigate-intercept-rejected.html
similarity index 79%
rename from testing/web-platform/tests/navigation-api/navigation-methods/return-value/navigate-transitionWhile-rejected.html
rename to testing/web-platform/tests/navigation-api/navigation-methods/return-value/navigate-intercept-rejected.html
index c1d4c4980251c..79c8bd803e346 100644
--- a/testing/web-platform/tests/navigation-api/navigation-methods/return-value/navigate-transitionWhile-rejected.html
+++ b/testing/web-platform/tests/navigation-api/navigation-methods/return-value/navigate-intercept-rejected.html
@@ -8,10 +8,10 @@
   const err = new Error("boo!");
   const promise = Promise.reject(err);
   promise.catch(() => {}); // prevent unhandled rejection testharness.js errors
-  navigation.onnavigate = e => e.transitionWhile(promise);
+  navigation.onnavigate = e => e.intercept({ handler: () => promise });
 
   const result = navigation.navigate("#1");
 
   await assertCommittedFulfillsFinishedRejectsExactly(t, result, navigation.currentEntry, err);
-}, "navigate() and transitionWhile() with a rejected promise");
+}, "navigate() and intercept() with a rejected promise");
 </script>
diff --git a/testing/web-platform/tests/navigation-api/navigation-methods/return-value/navigate-transitionWhile.html b/testing/web-platform/tests/navigation-api/navigation-methods/return-value/navigate-intercept.html
similarity index 71%
rename from testing/web-platform/tests/navigation-api/navigation-methods/return-value/navigate-transitionWhile.html
rename to testing/web-platform/tests/navigation-api/navigation-methods/return-value/navigate-intercept.html
index 2fe78e53e99f1..a9946c71ff3a8 100644
--- a/testing/web-platform/tests/navigation-api/navigation-methods/return-value/navigate-transitionWhile.html
+++ b/testing/web-platform/tests/navigation-api/navigation-methods/return-value/navigate-intercept.html
@@ -5,11 +5,11 @@
 
 <script>
 promise_test(async t => {
-  navigation.onnavigate = e => e.transitionWhile(Promise.resolve({ abc: 'def' }));
+  navigation.onnavigate = e => e.intercept({ handler: () => Promise.resolve({ abc: 'def' }) });
 
   const result = navigation.navigate("#1");
 
   await assertBothFulfill(t, result, navigation.currentEntry);
   assert_equals((new URL(navigation.currentEntry.url)).hash, "#1");
-}, "navigate() and transitionWhile() with a fulfilled promise");
+}, "navigate() and intercept() with a fulfilled promise");
 </script>
diff --git a/testing/web-platform/tests/navigation-api/navigation-methods/return-value/reload-transitionWhile-rejected.html b/testing/web-platform/tests/navigation-api/navigation-methods/return-value/reload-intercept-rejected.html
similarity index 79%
rename from testing/web-platform/tests/navigation-api/navigation-methods/return-value/reload-transitionWhile-rejected.html
rename to testing/web-platform/tests/navigation-api/navigation-methods/return-value/reload-intercept-rejected.html
index e6ec928a73685..93cd75c2b9986 100644
--- a/testing/web-platform/tests/navigation-api/navigation-methods/return-value/reload-transitionWhile-rejected.html
+++ b/testing/web-platform/tests/navigation-api/navigation-methods/return-value/reload-intercept-rejected.html
@@ -8,10 +8,10 @@
   const err = new Error("boo!");
   const promise = Promise.reject(err);
   promise.catch(() => {}); // prevent unhandled rejection testharness.js errors
-  navigation.onnavigate = e => e.transitionWhile(promise);
+  navigation.onnavigate = e => e.intercept({ handler: () => promise });
 
   const result = navigation.reload();
 
   await assertCommittedFulfillsFinishedRejectsExactly(t, result, navigation.currentEntry, err);
-}, "reload() and transitionWhile() with a rejected promise");
+}, "reload() and intercept() with a rejected promise");
 </script>
diff --git a/testing/web-platform/tests/navigation-api/navigation-methods/return-value/reload-transitionWhile.html b/testing/web-platform/tests/navigation-api/navigation-methods/return-value/reload-intercept.html
similarity index 67%
rename from testing/web-platform/tests/navigation-api/navigation-methods/return-value/reload-transitionWhile.html
rename to testing/web-platform/tests/navigation-api/navigation-methods/return-value/reload-intercept.html
index 19cea8afc2806..92f1636a6e85b 100644
--- a/testing/web-platform/tests/navigation-api/navigation-methods/return-value/reload-transitionWhile.html
+++ b/testing/web-platform/tests/navigation-api/navigation-methods/return-value/reload-intercept.html
@@ -5,10 +5,10 @@
 
 <script>
 promise_test(async t => {
-  navigation.onnavigate = e => e.transitionWhile(Promise.resolve({ abc: 'def' }));
+  navigation.onnavigate = e => e.intercept({ handler: () => Promise.resolve({ abc: 'def' }) });
 
   const result = navigation.reload();
 
   await assertBothFulfill(t, result, navigation.currentEntry);
-}, "reload() and transitionWhile() with a fulfilled promise");
+}, "reload() and intercept() with a fulfilled promise");
 </script>
diff --git a/testing/web-platform/tests/navigation-api/navigation-methods/return-value/reload.html b/testing/web-platform/tests/navigation-api/navigation-methods/return-value/reload.html
index 028d5855701ad..388f0d94b5030 100644
--- a/testing/web-platform/tests/navigation-api/navigation-methods/return-value/reload.html
+++ b/testing/web-platform/tests/navigation-api/navigation-methods/return-value/reload.html
@@ -12,5 +12,5 @@
   assertNeverSettles(t, result, i.contentWindow);
 
   await new Promise(resolve => i.onload = () => t.step_timeout(resolve, 0));
-}, "reload() promises never settle (without transitionWhile())");
+}, "reload() promises never settle (without intercept())");
 </script>
diff --git a/testing/web-platform/tests/navigation-api/navigation-methods/return-value/traverseTo-transitionWhile-rejected.html b/testing/web-platform/tests/navigation-api/navigation-methods/return-value/traverseTo-intercept-rejected.html
similarity index 88%
rename from testing/web-platform/tests/navigation-api/navigation-methods/return-value/traverseTo-transitionWhile-rejected.html
rename to testing/web-platform/tests/navigation-api/navigation-methods/return-value/traverseTo-intercept-rejected.html
index 613531023fa4b..f934eae5d4c1a 100644
--- a/testing/web-platform/tests/navigation-api/navigation-methods/return-value/traverseTo-transitionWhile-rejected.html
+++ b/testing/web-platform/tests/navigation-api/navigation-methods/return-value/traverseTo-intercept-rejected.html
@@ -21,10 +21,10 @@
   const err = new Error("boo!");
   const promise = Promise.reject(err);
   promise.catch(() => {}); // prevent unhandled rejection testharness.js errors
-  navigation.onnavigate = e => e.transitionWhile(promise);
+  navigation.onnavigate = e => e.intercept({ handler: () => promise });
 
   const result = navigation.traverseTo(key0);
   await assertCommittedFulfillsFinishedRejectsExactly(t, result, entry0, err);
   assert_equals(navigation.currentEntry, entry0);
-}, "traverseTo() promise rejection with rejected transitionWhile()");
+}, "traverseTo() promise rejection with rejected intercept()");
 </script>
diff --git a/testing/web-platform/tests/navigation-api/navigation-methods/return-value/traverseTo-transitionWhile.html b/testing/web-platform/tests/navigation-api/navigation-methods/return-value/traverseTo-intercept.html
similarity index 83%
rename from testing/web-platform/tests/navigation-api/navigation-methods/return-value/traverseTo-transitionWhile.html
rename to testing/web-platform/tests/navigation-api/navigation-methods/return-value/traverseTo-intercept.html
index 430fbe8be7921..a4cb4e711d8c9 100644
--- a/testing/web-platform/tests/navigation-api/navigation-methods/return-value/traverseTo-transitionWhile.html
+++ b/testing/web-platform/tests/navigation-api/navigation-methods/return-value/traverseTo-intercept.html
@@ -18,10 +18,10 @@
   assert_equals((new URL(entry0.url)).hash, "");
   assert_equals((new URL(entry1.url)).hash, "#1");
 
-  navigation.onnavigate = e => e.transitionWhile(Promise.resolve({ abc: "def" }));
+  navigation.onnavigate = e => e.intercept({ handler: () => Promise.resolve({ abc: "def" }) });
 
   const result = navigation.traverseTo(key0);
   await assertBothFulfill(t, result, entry0);
   assert_equals(navigation.currentEntry, entry0);
-}, "traverseTo() and transitionWhile() with a fulfilled promise");
+}, "traverseTo() and intercept() with a fulfilled promise");
 </script>
diff --git a/testing/web-platform/tests/navigation-api/navigation-methods/traverseTo-detach-between-navigate-and-navigatesuccess.html b/testing/web-platform/tests/navigation-api/navigation-methods/traverseTo-detach-between-navigate-and-navigatesuccess.html
index 25dd134649627..a0a2918887861 100644
--- a/testing/web-platform/tests/navigation-api/navigation-methods/traverseTo-detach-between-navigate-and-navigatesuccess.html
+++ b/testing/web-platform/tests/navigation-api/navigation-methods/traverseTo-detach-between-navigate-and-navigatesuccess.html
@@ -20,7 +20,7 @@
       let result;
 
       i.contentWindow.navigation.onnavigate = t.step_func(e => {
-        e.transitionWhile(new Promise(resolve => () => t.step_timeout(resolve, 2)));
+        e.intercept({ handler: () => new Promise(resolve => t.step_timeout(resolve, 2)) });
         t.step_timeout(() => i.remove(), 1);
       });
 
diff --git a/testing/web-platform/tests/navigation-api/ordering-and-transition/README.md b/testing/web-platform/tests/navigation-api/ordering-and-transition/README.md
index 653dd2198c3a2..628b22ec48b7d 100644
--- a/testing/web-platform/tests/navigation-api/ordering-and-transition/README.md
+++ b/testing/web-platform/tests/navigation-api/ordering-and-transition/README.md
@@ -15,10 +15,10 @@ Note:
   existing for `currententrychange` causes code to run, and thus microtasks to run,
   at a very specific point in the navigation-commit lifecycle. We want to test
   that it doesn't impact the ordering.
-* Similarly we test that `transitionWhile(Promise.resolve())` does not change
-  the ordering compared to no `transitionWhile()` call, for same-document
+* Similarly we test that `intercept()` does not change
+  the ordering compared to no `intercept()` call, for same-document
   navigations, by trying to ensure most variants have appropriate
-  `transitionWhile()` counterparts with similar orderings.
+  `intercept()` counterparts with similar orderings.
 
 TODOs:
 
diff --git a/testing/web-platform/tests/navigation-api/ordering-and-transition/anchor-download-transitionWhile-reject.html b/testing/web-platform/tests/navigation-api/ordering-and-transition/anchor-download-intercept-reject.html
similarity index 87%
rename from testing/web-platform/tests/navigation-api/ordering-and-transition/anchor-download-transitionWhile-reject.html
rename to testing/web-platform/tests/navigation-api/ordering-and-transition/anchor-download-intercept-reject.html
index 20202777a9f03..4869cedd2528e 100644
--- a/testing/web-platform/tests/navigation-api/ordering-and-transition/anchor-download-transitionWhile-reject.html
+++ b/testing/web-platform/tests/navigation-api/ordering-and-transition/anchor-download-intercept-reject.html
@@ -23,7 +23,10 @@
   recorder.setUpNavigationAPIListeners();
 
   navigation.addEventListener("navigate", e => {
-    e.transitionWhile(Promise.reject(expectedError));
+    e.intercept({ handler() {
+      recorder.record("handler run");
+      return Promise.reject(expectedError);
+    }});
   });
 
   let a = document.createElement("a");
@@ -40,11 +43,12 @@
     /* event name, location.hash value, navigation.transition properties */
     ["navigate", "", null],
     ["currententrychange", "#1", { from, navigationType: "push" }],
+    ["handler run", "#1", { from, navigationType: "push" }],
     ["promise microtask", "#1", { from, navigationType: "push" }],
     ["navigateerror", "#1", { from, navigationType: "push" }],
     ["transition.finished rejected", "#1", null],
   ]);
 
   recorder.assertErrorsAre(expectedError);
-}, "event and promise ordering for <a download> intercepted by passing a rejected promise to transitionWhile()");
+}, "event and promise ordering for <a download> intercepted by passing a rejected promise to intercept()");
 </script>
diff --git a/testing/web-platform/tests/navigation-api/ordering-and-transition/anchor-download-transitionWhile.html b/testing/web-platform/tests/navigation-api/ordering-and-transition/anchor-download-intercept.html
similarity index 87%
rename from testing/web-platform/tests/navigation-api/ordering-and-transition/anchor-download-transitionWhile.html
rename to testing/web-platform/tests/navigation-api/ordering-and-transition/anchor-download-intercept.html
index 822c0a230d506..23326c827b7a2 100644
--- a/testing/web-platform/tests/navigation-api/ordering-and-transition/anchor-download-transitionWhile.html
+++ b/testing/web-platform/tests/navigation-api/ordering-and-transition/anchor-download-intercept.html
@@ -22,7 +22,7 @@
   recorder.setUpNavigationAPIListeners();
 
   navigation.addEventListener("navigate", e => {
-    e.transitionWhile(Promise.resolve());
+    e.intercept({ handler() { recorder.record("handler run"); } });
   });
 
   let a = document.createElement("a");
@@ -39,9 +39,10 @@
     /* event name, location.hash value, navigation.transition properties */
     ["navigate", "", null],
     ["currententrychange", "#1", { from, navigationType: "push" }],
+    ["handler run", "#1", { from, navigationType: "push" }],
     ["promise microtask", "#1", { from, navigationType: "push" }],
     ["navigatesuccess", "#1", { from, navigationType: "push" }],
     ["transition.finished fulfilled", "#1", null],
   ]);
-}, "event and promise ordering for <a download> intercepted by transitionWhile()");
+}, "event and promise ordering for <a download> intercepted by intercept()");
 </script>
diff --git a/testing/web-platform/tests/navigation-api/ordering-and-transition/anchor-download.html b/testing/web-platform/tests/navigation-api/ordering-and-transition/anchor-download.html
index 0490069c7aa47..c6af13c3e0618 100644
--- a/testing/web-platform/tests/navigation-api/ordering-and-transition/anchor-download.html
+++ b/testing/web-platform/tests/navigation-api/ordering-and-transition/anchor-download.html
@@ -20,5 +20,5 @@
   i.contentWindow.navigation.onnavigateerror = t.unreached_func("navigateerror must not fire");
   await new Promise(resolve => t.step_timeout(resolve, 20));
   assert_true(navigate_called);
-}, "<a download> fires navigate, but not navigatesuccess or navigateerror when not intercepted by transitionWhile()");
+}, "<a download> fires navigate, but not navigatesuccess or navigateerror when not intercepted by intercept()");
 </script>
diff --git a/testing/web-platform/tests/navigation-api/ordering-and-transition/back-same-document-transitionWhile-reject.html b/testing/web-platform/tests/navigation-api/ordering-and-transition/back-same-document-intercept-reject.html
similarity index 87%
rename from testing/web-platform/tests/navigation-api/ordering-and-transition/back-same-document-transitionWhile-reject.html
rename to testing/web-platform/tests/navigation-api/ordering-and-transition/back-same-document-intercept-reject.html
index 05d86b4910213..c0d4f55027137 100644
--- a/testing/web-platform/tests/navigation-api/ordering-and-transition/back-same-document-transitionWhile-reject.html
+++ b/testing/web-platform/tests/navigation-api/ordering-and-transition/back-same-document-intercept-reject.html
@@ -24,7 +24,10 @@
   recorder.setUpNavigationAPIListeners();
 
   navigation.addEventListener("navigate", e => {
-    e.transitionWhile(Promise.reject(expectedError));
+    e.intercept({ handler() {
+      recorder.record("handler run");
+      return Promise.reject(expectedError);
+    }});
   });
 
   const result = navigation.back();
@@ -39,6 +42,7 @@
     ["promise microtask", "#1", null],
     ["navigate", "#1", null],
     ["currententrychange", "", { from, navigationType: "traverse" }],
+    ["handler run", "", { from, navigationType: "traverse" }],
     ["committed fulfilled", "", { from, navigationType: "traverse" }],
     ["navigateerror", "", { from, navigationType: "traverse" }],
     ["finished rejected", "", null],
@@ -46,5 +50,5 @@
   ]);
 
   recorder.assertErrorsAre(expectedError);
-}, "event and promise ordering for same-document navigation.back() intercepted by passing a rejected promise to transitionWhile()");
+}, "event and promise ordering for same-document navigation.back() intercepted by passing a rejected promise to intercept()");
 </script>
diff --git a/testing/web-platform/tests/navigation-api/ordering-and-transition/back-same-document-transitionWhile.html b/testing/web-platform/tests/navigation-api/ordering-and-transition/back-same-document-intercept.html
similarity index 90%
rename from testing/web-platform/tests/navigation-api/ordering-and-transition/back-same-document-transitionWhile.html
rename to testing/web-platform/tests/navigation-api/ordering-and-transition/back-same-document-intercept.html
index d435aab37b4b1..7bd248bc9c5a7 100644
--- a/testing/web-platform/tests/navigation-api/ordering-and-transition/back-same-document-transitionWhile.html
+++ b/testing/web-platform/tests/navigation-api/ordering-and-transition/back-same-document-intercept.html
@@ -23,7 +23,7 @@
   recorder.setUpNavigationAPIListeners();
 
   navigation.addEventListener("navigate", e => {
-    e.transitionWhile(Promise.resolve());
+    e.intercept({ handler() { recorder.record("handler run"); } });
   });
 
   const result = navigation.back();
@@ -38,10 +38,11 @@
     ["promise microtask", "#1", null],
     ["navigate", "#1", null],
     ["currententrychange", "", { from, navigationType: "traverse" }],
+    ["handler run", "", { from, navigationType: "traverse" }],
     ["committed fulfilled", "", { from, navigationType: "traverse" }],
     ["navigatesuccess", "", { from, navigationType: "traverse" }],
     ["finished fulfilled", "", null],
     ["transition.finished fulfilled", "", null]
   ]);
-}, "event and promise ordering for same-document navigation.back() intercepted by transitionWhile()");
+}, "event and promise ordering for same-document navigation.back() intercepted by intercept()");
 </script>
diff --git a/testing/web-platform/tests/navigation-api/ordering-and-transition/currententrychange-before-popstate-transitionWhile.html b/testing/web-platform/tests/navigation-api/ordering-and-transition/currententrychange-before-popstate-intercept.html
similarity index 96%
rename from testing/web-platform/tests/navigation-api/ordering-and-transition/currententrychange-before-popstate-transitionWhile.html
rename to testing/web-platform/tests/navigation-api/ordering-and-transition/currententrychange-before-popstate-intercept.html
index 59f37e97125e6..c51c7c444cb9a 100644
--- a/testing/web-platform/tests/navigation-api/ordering-and-transition/currententrychange-before-popstate-transitionWhile.html
+++ b/testing/web-platform/tests/navigation-api/ordering-and-transition/currententrychange-before-popstate-intercept.html
@@ -9,7 +9,7 @@
   await navigation.navigate("#foo").committed;
   assert_equals(navigation.entries().length, 2);
 
-  navigation.onnavigate = e => e.transitionWhile(Promise.resolve());
+  navigation.onnavigate = e => e.intercept();
 
   let oncurrententrychange_back_called = false;
   let onpopstate_back_called = false;
diff --git a/testing/web-platform/tests/navigation-api/ordering-and-transition/intercept-async.html b/testing/web-platform/tests/navigation-api/ordering-and-transition/intercept-async.html
new file mode 100644
index 0000000000000..f2ca0969506bb
--- /dev/null
+++ b/testing/web-platform/tests/navigation-api/ordering-and-transition/intercept-async.html
@@ -0,0 +1,55 @@
+<!doctype html>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<meta name="variant" content="">
+<meta name="variant" content="?currententrychange">
+
+<script type="module">
+import { Recorder, hasVariant } from "./resources/helpers.mjs";
+
+promise_test(async t => {
+  // Wait for after the load event so that the navigation doesn't get converted
+  // into a replace navigation.
+  await new Promise(resolve => window.onload = () => t.step_timeout(resolve, 0));
+
+  const from = navigation.currentEntry;
+
+  const recorder = new Recorder({
+    skipCurrentChange: !hasVariant("currententrychange"),
+    finalExpectedEvent: "transition.finished fulfilled"
+  });
+
+  recorder.setUpNavigationAPIListeners();
+
+  navigation.addEventListener("navigate", e => {
+    e.intercept({ async handler() {
+      recorder.record("handler sync");
+      await Promise.resolve();
+      recorder.record("handler after microtask");
+      await new Promise(r => t.step_timeout(r, 0));
+      recorder.record("handler after setTimeout");
+    } });
+  });
+
+  const result = navigation.navigate("#1");
+  recorder.setUpResultListeners(result);
+
+  Promise.resolve().then(() => recorder.record("promise microtask"));
+
+  await recorder.readyToAssert;
+
+  recorder.assert([
+    /* event name, location.hash value, navigation.transition properties */
+    ["navigate", "", null],
+    ["currententrychange", "#1", { from, navigationType: "push" }],
+    ["handler sync", "#1", { from, navigationType: "push" }],
+    ["handler after microtask", "#1", { from, navigationType: "push" }],
+    ["committed fulfilled", "#1", { from, navigationType: "push" }],
+    ["promise microtask", "#1", { from, navigationType: "push" }],
+    ["handler after setTimeout", "#1", { from, navigationType: "push" }],
+    ["navigatesuccess", "#1", { from, navigationType: "push" }],
+    ["finished fulfilled", "#1", null],
+    ["transition.finished fulfilled", "#1", null],
+  ]);
+}, "ordering when intercept() handler has sync and async blocks");
+</script>
diff --git a/testing/web-platform/tests/navigation-api/ordering-and-transition/location-href-double-transitionWhile.html b/testing/web-platform/tests/navigation-api/ordering-and-transition/location-href-double-intercept.html
similarity index 86%
rename from testing/web-platform/tests/navigation-api/ordering-and-transition/location-href-double-transitionWhile.html
rename to testing/web-platform/tests/navigation-api/ordering-and-transition/location-href-double-intercept.html
index 5ec22b119fa67..36ae5ce4ab52b 100644
--- a/testing/web-platform/tests/navigation-api/ordering-and-transition/location-href-double-transitionWhile.html
+++ b/testing/web-platform/tests/navigation-api/ordering-and-transition/location-href-double-intercept.html
@@ -22,7 +22,10 @@
   recorder.setUpNavigationAPIListeners();
 
   navigation.addEventListener("navigate", e => {
-    e.transitionWhile(new Promise(r => t.step_timeout(r, 1)));
+    e.intercept({ handler() {
+      recorder.record("handler run");
+      return new Promise(r => t.step_timeout(r, 1));
+    }});
 
     if (location.hash === "#1") {
       fromHash1 = navigation.currentEntry;
@@ -40,11 +43,13 @@
     /* event name, location.hash value, navigation.transition properties */
     ["navigate", "", null],
     ["currententrychange", "#1", { from: fromStart, navigationType: "push" }],
+    ["handler run", "#1", { from: fromStart, navigationType: "push" }],
     ["AbortSignal abort", "#1", { from: fromStart, navigationType: "push" }],
     ["navigateerror", "#1", { from: fromStart, navigationType: "push" }],
 
     ["navigate", "#1", null],
     ["currententrychange", "#2", { from: fromHash1, navigationType: "push" }],
+    ["handler run", "#2", { from: fromHash1, navigationType: "push" }],
     ["transition.finished rejected", "#2", { from: fromHash1, navigationType: "push" }],
     ["promise microtask", "#2", { from: fromHash1, navigationType: "push" }],
     ["navigatesuccess", "#2", { from: fromHash1, navigationType: "push" }],
@@ -52,5 +57,5 @@
   ]);
 
   recorder.assertErrorsAreAbortErrors();
-}, "event and promise ordering when location.href is set repeatedly and handled by transitionWhile()");
+}, "event and promise ordering when location.href is set repeatedly and handled by intercept()");
 </script>
diff --git a/testing/web-platform/tests/navigation-api/ordering-and-transition/location-href-transitionWhile-reentrant.html b/testing/web-platform/tests/navigation-api/ordering-and-transition/location-href-intercept-reentrant.html
similarity index 85%
rename from testing/web-platform/tests/navigation-api/ordering-and-transition/location-href-transitionWhile-reentrant.html
rename to testing/web-platform/tests/navigation-api/ordering-and-transition/location-href-intercept-reentrant.html
index 4dedb58d5b042..3fabf52bfbab2 100644
--- a/testing/web-platform/tests/navigation-api/ordering-and-transition/location-href-transitionWhile-reentrant.html
+++ b/testing/web-platform/tests/navigation-api/ordering-and-transition/location-href-intercept-reentrant.html
@@ -23,7 +23,10 @@
   recorder.setUpNavigationAPIListeners();
 
   navigation.addEventListener("navigate", e => {
-    e.transitionWhile(new Promise(resolve => t.step_timeout(resolve, 2)));
+    e.intercept({ handler() {
+      recorder.record("handler run");
+      return new Promise(resolve => t.step_timeout(resolve, 2));
+    }});
 
     if (firstNavigate) {
       firstNavigate = false;
@@ -46,11 +49,12 @@
 
     ["navigate", "", null],
     ["currententrychange", "#2", { from, navigationType: "push" }],
+    ["handler run", "#2", { from, navigationType: "push" }],
     ["promise microtask", "#2", { from, navigationType: "push" }],
     ["navigatesuccess", "#2", { from, navigationType: "push" }],
     ["transition.finished fulfilled", "#2", null]
   ]);
 
   recorder.assertErrorsAreAbortErrors();
-}, "event and promise ordering for the location.href setter intercepted by transitionWhile() where we set location.href again inside the navigate handler");
+}, "event and promise ordering for the location.href setter intercepted by intercept() where we set location.href again inside the navigate handler");
 </script>
diff --git a/testing/web-platform/tests/navigation-api/ordering-and-transition/location-href-transitionWhile-reject.html b/testing/web-platform/tests/navigation-api/ordering-and-transition/location-href-intercept-reject.html
similarity index 86%
rename from testing/web-platform/tests/navigation-api/ordering-and-transition/location-href-transitionWhile-reject.html
rename to testing/web-platform/tests/navigation-api/ordering-and-transition/location-href-intercept-reject.html
index dbef3928e30c9..b4aeb726b3b59 100644
--- a/testing/web-platform/tests/navigation-api/ordering-and-transition/location-href-transitionWhile-reject.html
+++ b/testing/web-platform/tests/navigation-api/ordering-and-transition/location-href-intercept-reject.html
@@ -23,7 +23,10 @@
   recorder.setUpNavigationAPIListeners();
 
   navigation.addEventListener("navigate", e => {
-    e.transitionWhile(Promise.reject(expectedError));
+    e.intercept({ handler() {
+      recorder.record("handler run");
+      return Promise.reject(expectedError);
+    }});
   });
 
   location.href = "/common/blank.html#1";
@@ -36,11 +39,12 @@
     /* event name, location.hash value, navigation.transition properties */
     ["navigate", "", null],
     ["currententrychange", "#1", { from, navigationType: "push" }],
+    ["handler run", "#1", { from, navigationType: "push" }],
     ["promise microtask", "#1", { from, navigationType: "push" }],
     ["navigateerror", "#1", { from, navigationType: "push" }],
     ["transition.finished rejected", "#1", null],
   ]);
 
   recorder.assertErrorsAre(expectedError);
-}, "event and promise ordering for location.href setter intercepted by passing a rejected promise to transitionWhile()");
+}, "event and promise ordering for location.href setter intercepted by passing a rejected promise to intercept()");
 </script>
diff --git a/testing/web-platform/tests/navigation-api/ordering-and-transition/location-href-transitionWhile.html b/testing/web-platform/tests/navigation-api/ordering-and-transition/location-href-intercept.html
similarity index 90%
rename from testing/web-platform/tests/navigation-api/ordering-and-transition/location-href-transitionWhile.html
rename to testing/web-platform/tests/navigation-api/ordering-and-transition/location-href-intercept.html
index 0e1d22df7254f..bb861d37ae54a 100644
--- a/testing/web-platform/tests/navigation-api/ordering-and-transition/location-href-transitionWhile.html
+++ b/testing/web-platform/tests/navigation-api/ordering-and-transition/location-href-intercept.html
@@ -22,7 +22,7 @@
   recorder.setUpNavigationAPIListeners();
 
   navigation.addEventListener("navigate", e => {
-    e.transitionWhile(Promise.resolve());
+    e.intercept({ handler() { recorder.record("handler run"); } });
   });
 
   location.href = "/common/blank.html#1";
@@ -35,9 +35,10 @@
     /* event name, location.hash value, navigation.transition properties */
     ["navigate", "", null],
     ["currententrychange", "#1", { from, navigationType: "push" }],
+    ["handler run", "#1", { from, navigationType: "push" }],
     ["promise microtask", "#1", { from, navigationType: "push" }],
     ["navigatesuccess", "#1", { from, navigationType: "push" }],
     ["transition.finished fulfilled", "#1", null],
   ]);
-}, "event and promise ordering for location.href setter intercepted by transitionWhile()");
+}, "event and promise ordering for location.href setter intercepted by intercept()");
 </script>
diff --git a/testing/web-platform/tests/navigation-api/ordering-and-transition/navigate-double-transitionWhile.html b/testing/web-platform/tests/navigation-api/ordering-and-transition/navigate-double-intercept.html
similarity index 88%
rename from testing/web-platform/tests/navigation-api/ordering-and-transition/navigate-double-transitionWhile.html
rename to testing/web-platform/tests/navigation-api/ordering-and-transition/navigate-double-intercept.html
index 556d1737a6e37..6ce67b9af644a 100644
--- a/testing/web-platform/tests/navigation-api/ordering-and-transition/navigate-double-transitionWhile.html
+++ b/testing/web-platform/tests/navigation-api/ordering-and-transition/navigate-double-intercept.html
@@ -22,7 +22,10 @@
   recorder.setUpNavigationAPIListeners();
 
   navigation.addEventListener("navigate", e => {
-    e.transitionWhile(new Promise(r => t.step_timeout(r, 1)));
+    e.intercept({ handler() {
+      recorder.record("handler run");
+      return new Promise(r => t.step_timeout(r, 1));
+    }});
 
     if (location.hash === "#1") {
       fromHash1 = navigation.currentEntry;
@@ -43,11 +46,13 @@
     /* event name, location.hash value, navigation.transition properties */
     ["navigate", "", null],
     ["currententrychange", "#1", { from: fromStart, navigationType: "push" }],
+    ["handler run", "#1", { from: fromStart, navigationType: "push" }],
     ["AbortSignal abort", "#1", { from: fromStart, navigationType: "push" }],
     ["navigateerror", "#1", { from: fromStart, navigationType: "push" }],
 
     ["navigate", "#1", null],
     ["currententrychange", "#2", { from: fromHash1, navigationType: "push" }],
+    ["handler run", "#2", { from: fromHash1, navigationType: "push" }],
     ["committed fulfilled 1", "#2", { from: fromHash1, navigationType: "push" }],
     ["finished rejected 1", "#2", { from: fromHash1, navigationType: "push" }],
     ["transition.finished rejected", "#2", { from: fromHash1, navigationType: "push" }],
@@ -59,5 +64,5 @@
   ]);
 
   recorder.assertErrorsAreAbortErrors();
-}, "event and promise ordering when navigate() is called repeatedly and handled by transitionWhile()");
+}, "event and promise ordering when navigate() is called repeatedly and handled by intercept()");
 </script>
diff --git a/testing/web-platform/tests/navigation-api/ordering-and-transition/navigate-in-transition-finished.html b/testing/web-platform/tests/navigation-api/ordering-and-transition/navigate-in-transition-finished.html
index 8c74ba2f632f7..9251cfe049d30 100644
--- a/testing/web-platform/tests/navigation-api/ordering-and-transition/navigate-in-transition-finished.html
+++ b/testing/web-platform/tests/navigation-api/ordering-and-transition/navigate-in-transition-finished.html
@@ -32,7 +32,7 @@
   }));
 
   navigation.addEventListener("navigate", e => {
-    e.transitionWhile(Promise.resolve());
+    e.intercept({ handler() { recorder.record("handler run"); } });
 
     if (location.hash === "#1") {
       fromHash1 = navigation.currentEntry;
@@ -50,6 +50,7 @@
     /* event name, location.hash value, navigation.transition properties */
     ["navigate", "", null],
     ["currententrychange", "#1", { from: fromStart, navigationType: "push" }],
+    ["handler run", "#1", { from: fromStart, navigationType: "push" }],
     ["committed fulfilled 1", "#1", { from: fromStart, navigationType: "push" }],
     ["promise microtask", "#1", { from: fromStart, navigationType: "push" }],
     ["navigatesuccess", "#1", { from: fromStart, navigationType: "push" }],
@@ -58,6 +59,7 @@
 
     ["navigate", "#1", null],
     ["currententrychange", "#2", { from: fromHash1, navigationType: "push" }],
+    ["handler run", "#2", { from: fromHash1, navigationType: "push" }],
     ["committed fulfilled 2", "#2", { from: fromHash1, navigationType: "push" }],
     ["navigatesuccess", "#2", { from: fromHash1, navigationType: "push" }],
     ["finished fulfilled 2", "#2", null],
diff --git a/testing/web-platform/tests/navigation-api/ordering-and-transition/navigate-transitionWhile-stop.html b/testing/web-platform/tests/navigation-api/ordering-and-transition/navigate-intercept-stop.html
similarity index 89%
rename from testing/web-platform/tests/navigation-api/ordering-and-transition/navigate-transitionWhile-stop.html
rename to testing/web-platform/tests/navigation-api/ordering-and-transition/navigate-intercept-stop.html
index 9a8c412b3333e..5d126a8c2ff9b 100644
--- a/testing/web-platform/tests/navigation-api/ordering-and-transition/navigate-transitionWhile-stop.html
+++ b/testing/web-platform/tests/navigation-api/ordering-and-transition/navigate-intercept-stop.html
@@ -22,7 +22,7 @@
   recorder.setUpNavigationAPIListeners();
 
   navigation.addEventListener("navigate", e => {
-    e.transitionWhile(Promise.resolve());
+    e.intercept({ handler() { recorder.record("handler run"); } });
   });
 
   const result = navigation.navigate("/common/blank.html#1");
@@ -38,6 +38,7 @@
     /* event name, location.hash value, navigation.transition properties */
     ["navigate", "", null],
     ["currententrychange", "#1", { from, navigationType: "push" }],
+    ["handler run", "#1", { from, navigationType: "push" }],
     ["AbortSignal abort", "#1", { from, navigationType: "push" }],
     ["navigateerror", "#1", { from, navigationType: "push" }],
     ["committed fulfilled", "#1", null],
@@ -47,5 +48,5 @@
   ]);
 
   recorder.assertErrorsAreAbortErrors();
-}, "event and promise ordering for navigation.navigate() intercepted by transitionWhile() but then stopped using window.stop()");
+}, "event and promise ordering for navigation.navigate() intercepted by intercept() but then stopped using window.stop()");
 </script>
diff --git a/testing/web-platform/tests/navigation-api/ordering-and-transition/navigate-transitionWhile.html b/testing/web-platform/tests/navigation-api/ordering-and-transition/navigate-intercept.html
similarity index 90%
rename from testing/web-platform/tests/navigation-api/ordering-and-transition/navigate-transitionWhile.html
rename to testing/web-platform/tests/navigation-api/ordering-and-transition/navigate-intercept.html
index b72bf49eae20f..f76f20bf85efa 100644
--- a/testing/web-platform/tests/navigation-api/ordering-and-transition/navigate-transitionWhile.html
+++ b/testing/web-platform/tests/navigation-api/ordering-and-transition/navigate-intercept.html
@@ -22,7 +22,7 @@
   recorder.setUpNavigationAPIListeners();
 
   navigation.addEventListener("navigate", e => {
-    e.transitionWhile(Promise.resolve());
+    e.intercept({ handler() { recorder.record("handler run"); } });
   });
 
   const result = navigation.navigate("#1");
@@ -36,11 +36,12 @@
     /* event name, location.hash value, navigation.transition properties */
     ["navigate", "", null],
     ["currententrychange", "#1", { from, navigationType: "push" }],
+    ["handler run", "#1", { from, navigationType: "push" }],
     ["committed fulfilled", "#1", { from, navigationType: "push" }],
     ["promise microtask", "#1", { from, navigationType: "push" }],
     ["navigatesuccess", "#1", { from, navigationType: "push" }],
     ["finished fulfilled", "#1", null],
     ["transition.finished fulfilled", "#1", null],
   ]);
-}, "event and promise ordering for same-document navigation.navigate() intercepted by transitionWhile()");
+}, "event and promise ordering for same-document navigation.navigate() intercepted by intercept()");
 </script>
diff --git a/testing/web-platform/tests/navigation-api/ordering-and-transition/navigate-same-document-transitionWhile-reentrant.html b/testing/web-platform/tests/navigation-api/ordering-and-transition/navigate-same-document-intercept-reentrant.html
similarity index 91%
rename from testing/web-platform/tests/navigation-api/ordering-and-transition/navigate-same-document-transitionWhile-reentrant.html
rename to testing/web-platform/tests/navigation-api/ordering-and-transition/navigate-same-document-intercept-reentrant.html
index 2ef4c4fe27294..86f4e06731353 100644
--- a/testing/web-platform/tests/navigation-api/ordering-and-transition/navigate-same-document-transitionWhile-reentrant.html
+++ b/testing/web-platform/tests/navigation-api/ordering-and-transition/navigate-same-document-intercept-reentrant.html
@@ -23,7 +23,10 @@
   recorder.setUpNavigationAPIListeners();
 
   navigation.addEventListener("navigate", e => {
-    e.transitionWhile(new Promise(resolve => t.step_timeout(resolve, 2)));
+    e.intercept({ handler() {
+      recorder.record("handler run");
+      return new Promise(r => t.step_timeout(r, 2));
+    }});
 
     if (firstNavigate) {
       firstNavigate = false;
@@ -48,6 +51,7 @@
 
     ["navigate", "", null],
     ["currententrychange", "#2", { from, navigationType: "push" }],
+    ["handler run", "#2", { from, navigationType: "push" }],
     ["committed fulfilled 2", "#2", { from, navigationType: "push" }],
     ["committed rejected 1", "#2", { from, navigationType: "push" }],
     ["finished rejected 1", "#2", { from, navigationType: "push" }],
diff --git a/testing/web-platform/tests/navigation-api/ordering-and-transition/navigate-same-document-transitionWhile-reject.html b/testing/web-platform/tests/navigation-api/ordering-and-transition/navigate-same-document-intercept-reject.html
similarity index 86%
rename from testing/web-platform/tests/navigation-api/ordering-and-transition/navigate-same-document-transitionWhile-reject.html
rename to testing/web-platform/tests/navigation-api/ordering-and-transition/navigate-same-document-intercept-reject.html
index b3a10b422e944..88c668e0e99e8 100644
--- a/testing/web-platform/tests/navigation-api/ordering-and-transition/navigate-same-document-transitionWhile-reject.html
+++ b/testing/web-platform/tests/navigation-api/ordering-and-transition/navigate-same-document-intercept-reject.html
@@ -23,7 +23,10 @@
   recorder.setUpNavigationAPIListeners();
 
   navigation.addEventListener("navigate", e => {
-    e.transitionWhile(Promise.reject(expectedError));
+    e.intercept({ handler() {
+      recorder.record("handler run");
+      return Promise.reject(expectedError);
+    }});
   });
 
   const result = navigation.navigate("#1");
@@ -37,6 +40,7 @@
     /* event name, location.hash value, navigation.transition properties */
     ["navigate", "", null],
     ["currententrychange", "#1", { from, navigationType: "push" }],
+    ["handler run", "#1", { from, navigationType: "push" }],
     ["committed fulfilled", "#1", { from, navigationType: "push" }],
     ["promise microtask", "#1", { from, navigationType: "push" }],
     ["navigateerror", "#1", { from, navigationType: "push" }],
@@ -45,5 +49,5 @@
   ]);
 
   recorder.assertErrorsAre(expectedError);
-}, "event and promise ordering for same-document navigation.navigate() intercepted by passing a rejected promise to transitionWhile()");
+}, "event and promise ordering for same-document navigation.navigate() intercepted by passing a rejected promise to intercept()");
 </script>
diff --git a/testing/web-platform/tests/navigation-api/ordering-and-transition/reload-transitionWhile-reject.html b/testing/web-platform/tests/navigation-api/ordering-and-transition/reload-intercept-reject.html
similarity index 88%
rename from testing/web-platform/tests/navigation-api/ordering-and-transition/reload-transitionWhile-reject.html
rename to testing/web-platform/tests/navigation-api/ordering-and-transition/reload-intercept-reject.html
index 6939ee2df8208..334d2108ecdc2 100644
--- a/testing/web-platform/tests/navigation-api/ordering-and-transition/reload-transitionWhile-reject.html
+++ b/testing/web-platform/tests/navigation-api/ordering-and-transition/reload-intercept-reject.html
@@ -23,7 +23,10 @@
   recorder.setUpNavigationAPIListeners();
 
   navigation.addEventListener("navigate", e => {
-    e.transitionWhile(Promise.reject(expectedError));
+    e.intercept({ handler() {
+      recorder.record("handler run");
+      return Promise.reject(expectedError);
+    }});
   });
 
   const result = navigation.reload();
@@ -37,6 +40,7 @@
     /* event name, location.hash value, navigation.transition properties */
     ["navigate", "", null],
     ["currententrychange", "", { from, navigationType: "reload" }],
+    ["handler run", "", { from, navigationType: "reload" }],
     ["committed fulfilled", "", { from, navigationType: "reload" }],
     ["promise microtask", "", { from, navigationType: "reload" }],
     ["navigateerror", "", { from, navigationType: "reload" }],
@@ -45,5 +49,5 @@
   ]);
 
   recorder.assertErrorsAre(expectedError);
-}, "event and promise ordering for navigation.reload() intercepted by transitionWhile()");
+}, "event and promise ordering for navigation.reload() intercepted by intercept()");
 </script>
diff --git a/testing/web-platform/tests/navigation-api/ordering-and-transition/reload-transitionWhile.html b/testing/web-platform/tests/navigation-api/ordering-and-transition/reload-intercept.html
similarity index 91%
rename from testing/web-platform/tests/navigation-api/ordering-and-transition/reload-transitionWhile.html
rename to testing/web-platform/tests/navigation-api/ordering-and-transition/reload-intercept.html
index 31cd813f7419b..8d4160a4d959f 100644
--- a/testing/web-platform/tests/navigation-api/ordering-and-transition/reload-transitionWhile.html
+++ b/testing/web-platform/tests/navigation-api/ordering-and-transition/reload-intercept.html
@@ -22,7 +22,7 @@
   recorder.setUpNavigationAPIListeners();
 
   navigation.addEventListener("navigate", e => {
-    e.transitionWhile(Promise.resolve());
+    e.intercept({ handler() { recorder.record("handler run"); } });
   });
 
   const result = navigation.reload();
@@ -36,11 +36,12 @@
     /* event name, location.hash value, navigation.transition properties */
     ["navigate", "", null],
     ["currententrychange", "", { from, navigationType: "reload" }],
+    ["handler run", "", { from, navigationType: "reload" }],
     ["committed fulfilled", "", { from, navigationType: "reload" }],
     ["promise microtask", "", { from, navigationType: "reload" }],
     ["navigatesuccess", "", { from, navigationType: "reload" }],
     ["finished fulfilled", "", null],
     ["transition.finished fulfilled", "", null],
   ]);
-}, "event and promise ordering for navigation.reload() intercepted by transitionWhile()");
+}, "event and promise ordering for navigation.reload() intercepted by intercept()");
 </script>
diff --git a/testing/web-platform/tests/navigation-api/ordering-and-transition/transition-finished-mark-as-handled.html b/testing/web-platform/tests/navigation-api/ordering-and-transition/transition-finished-mark-as-handled.html
index 859e07df13970..fa38b822166ee 100644
--- a/testing/web-platform/tests/navigation-api/ordering-and-transition/transition-finished-mark-as-handled.html
+++ b/testing/web-platform/tests/navigation-api/ordering-and-transition/transition-finished-mark-as-handled.html
@@ -5,7 +5,7 @@
 <script>
 async_test(t => {
   navigation.addEventListener("navigate", e => {
-    e.transitionWhile(Promise.reject(new Error("oh no!")));
+    e.intercept({ handler: () => Promise.reject(new Error("oh no!")) });
   });
 
   window.onunhandledrejection = t.unreached_func("unhandledrejection must not fire");
diff --git a/testing/web-platform/tests/navigation-api/ordering-and-transition/transition-realms-and-identity.html b/testing/web-platform/tests/navigation-api/ordering-and-transition/transition-realms-and-identity.html
index c2c06fcca2604..f1b3ead980794 100644
--- a/testing/web-platform/tests/navigation-api/ordering-and-transition/transition-realms-and-identity.html
+++ b/testing/web-platform/tests/navigation-api/ordering-and-transition/transition-realms-and-identity.html
@@ -9,7 +9,7 @@
   await new Promise(resolve => window.onload = resolve);
 
   i.contentWindow.navigation.addEventListener("navigate", e => {
-    e.transitionWhile(Promise.resolve());
+    e.intercept();
   });
 
   const returnValueFinished1 = i.contentWindow.navigation.navigate("?1").finished;
diff --git a/testing/web-platform/tests/navigation-api/per-entry-events/dispose-same-document-transitionWhile.html b/testing/web-platform/tests/navigation-api/per-entry-events/dispose-same-document-intercept.html
similarity index 98%
rename from testing/web-platform/tests/navigation-api/per-entry-events/dispose-same-document-transitionWhile.html
rename to testing/web-platform/tests/navigation-api/per-entry-events/dispose-same-document-intercept.html
index 2c0b92e7ad9a8..44aa096aafec7 100644
--- a/testing/web-platform/tests/navigation-api/per-entry-events/dispose-same-document-transitionWhile.html
+++ b/testing/web-platform/tests/navigation-api/per-entry-events/dispose-same-document-intercept.html
@@ -55,7 +55,7 @@
   await navigation.traverseTo(entry1.key).committed;
 
   navigation.addEventListener("navigate", e => {
-    e.transitionWhile(Promise.resolve());
+    e.intercept();
   });
 
   navigation.navigate("#fork");
diff --git a/testing/web-platform/tests/navigation-api/per-entry-events/dispose-same-document-reload-with-transitionWhile.html b/testing/web-platform/tests/navigation-api/per-entry-events/dispose-same-document-reload-with-intercept.html
similarity index 79%
rename from testing/web-platform/tests/navigation-api/per-entry-events/dispose-same-document-reload-with-transitionWhile.html
rename to testing/web-platform/tests/navigation-api/per-entry-events/dispose-same-document-reload-with-intercept.html
index b55bfb4132923..1e083714f65e8 100644
--- a/testing/web-platform/tests/navigation-api/per-entry-events/dispose-same-document-reload-with-transitionWhile.html
+++ b/testing/web-platform/tests/navigation-api/per-entry-events/dispose-same-document-reload-with-intercept.html
@@ -10,8 +10,8 @@
 
   navigation.currentEntry.ondispose = t.unreached_func("dispose must not happen for reloads");
 
-  navigation.addEventListener("navigate", e => e.transitionWhile(Promise.resolve()));
+  navigation.addEventListener("navigate", e => e.intercept());
 
   await navigation.reload().finished;
-}, "dispose events are not fired when doing a same-document reload using navigation.reload() and transitionWhile()");
+}, "dispose events are not fired when doing a same-document reload using navigation.reload() and intercept()");
 </script>
diff --git a/testing/web-platform/tests/navigation-api/per-entry-events/dispose-same-document-replace-with-transitionWhile.html b/testing/web-platform/tests/navigation-api/per-entry-events/dispose-same-document-replace-with-intercept.html
similarity index 91%
rename from testing/web-platform/tests/navigation-api/per-entry-events/dispose-same-document-replace-with-transitionWhile.html
rename to testing/web-platform/tests/navigation-api/per-entry-events/dispose-same-document-replace-with-intercept.html
index bcb0f02d75d34..4e492e30aedeb 100644
--- a/testing/web-platform/tests/navigation-api/per-entry-events/dispose-same-document-replace-with-transitionWhile.html
+++ b/testing/web-platform/tests/navigation-api/per-entry-events/dispose-same-document-replace-with-intercept.html
@@ -28,9 +28,9 @@
     assert_equals(location.search, "?replacement");
   });
 
-  navigation.addEventListener("navigate", e => e.transitionWhile(Promise.resolve()));
+  navigation.addEventListener("navigate", e => e.intercept());
 
   navigation.navigate("?replacement", { history: "replace" });
   assert_true(disposeCalled);
-}, "dispose events when doing a same-document replace using navigation.navigate() and transitionWhile()");
+}, "dispose events when doing a same-document replace using navigation.navigate() and intercept()");
 </script>
diff --git a/testing/web-platform/tests/navigation-api/scroll-restoration/after-transition-basic.html b/testing/web-platform/tests/navigation-api/scroll-restoration/after-transition-basic.html
index 647b12ba7d011..8270f8e2ad33d 100644
--- a/testing/web-platform/tests/navigation-api/scroll-restoration/after-transition-basic.html
+++ b/testing/web-platform/tests/navigation-api/scroll-restoration/after-transition-basic.html
@@ -12,7 +12,7 @@
   assert_equals(window.scrollY, 0);
   await navigation.navigate("#frag").finished;
   assert_not_equals(window.scrollY, 0);
-  navigation.onnavigate = e => e.transitionWhile(Promise.resolve(), { scrollRestoration: "after-transition" });
+  navigation.onnavigate = e => e.intercept({ scrollRestoration: "after-transition" });
   await navigation.back().finished;
   assert_equals(window.scrollY, 0);
 }, "scrollRestoration: after-transition should scroll when back completes");
diff --git a/testing/web-platform/tests/navigation-api/scroll-restoration/after-transition-change-history-scroll-restoration-during-promise.html b/testing/web-platform/tests/navigation-api/scroll-restoration/after-transition-change-history-scroll-restoration-during-promise.html
index 5e60ca33721c2..2e762379a5314 100644
--- a/testing/web-platform/tests/navigation-api/scroll-restoration/after-transition-change-history-scroll-restoration-during-promise.html
+++ b/testing/web-platform/tests/navigation-api/scroll-restoration/after-transition-change-history-scroll-restoration-during-promise.html
@@ -15,15 +15,16 @@
   await navigation.navigate("#frag").finished;
   assert_not_equals(window.scrollY, 0);
 
-  let transitionWhile_resolve;
+  let intercept_resolve;
   navigation.onnavigate = e => {
-    e.transitionWhile(new Promise(r => transitionWhile_resolve = r), { scrollRestoration: "after-transition" });
+    e.intercept({ handler: () => new Promise(r => intercept_resolve = r),
+                  scrollRestoration: "after-transition" });
   };
 
   let back_promises = navigation.back();
   await back_promises.committed;
   history.scrollRestoration = "auto";
-  transitionWhile_resolve();
+  intercept_resolve();
   await back_promises.finished;
   assert_equals(window.scrollY, 0);
 }, "scrollRestoration: after-transition should ignore history.scrollRestoration even if it changes in the middle of the navigation");
diff --git a/testing/web-platform/tests/navigation-api/scroll-restoration/after-transition-intercept-handler-modifies.html b/testing/web-platform/tests/navigation-api/scroll-restoration/after-transition-intercept-handler-modifies.html
new file mode 100644
index 0000000000000..a11c04c3250cc
--- /dev/null
+++ b/testing/web-platform/tests/navigation-api/scroll-restoration/after-transition-intercept-handler-modifies.html
@@ -0,0 +1,33 @@
+<!doctype html>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<body>
+<div id="main" style="height: 1000px; width: 1000px;"></div>
+<script>
+promise_test(async t => {
+  // Wait for after the load event so that the navigation doesn't get converted
+  // into a replace navigation.
+  await new Promise(resolve => window.onload = () => t.step_timeout(resolve, 0));
+  assert_equals(window.scrollY, 0);
+  window.scrollTo(0, 100);
+  assert_equals(window.scrollY, 100);
+  navigation.onnavigate = e => e.intercept(
+    { scrollRestoration: "after-transition",
+      handler: async () => {
+        if (e.navigationType == "push") {
+          // Inserting this <div> should scroll *after* the scroll position
+          // is saved, so that it doesn't break scroll restoration when going
+          // back.
+          let div = document.createElement("div");
+          div.style = "height: 1000px; width: 1000px;";
+          document.body.insertBefore(div, main);
+        }
+      }
+    }
+  );
+  await navigation.navigate("?go").finished;
+  await navigation.back().finished;
+  assert_equals(window.scrollY, 100);
+}, "scrollRestoration: state should be saved before intercept handlers run");
+</script>
+</body>
diff --git a/testing/web-platform/tests/navigation-api/scroll-restoration/after-transition-reject.html b/testing/web-platform/tests/navigation-api/scroll-restoration/after-transition-reject.html
index 7a75b8abd037f..b1cfcede3ee71 100644
--- a/testing/web-platform/tests/navigation-api/scroll-restoration/after-transition-reject.html
+++ b/testing/web-platform/tests/navigation-api/scroll-restoration/after-transition-reject.html
@@ -12,10 +12,12 @@
   assert_equals(window.scrollY, 0);
   await navigation.navigate("#frag").finished;
   assert_not_equals(window.scrollY, 0);
-  navigation.onnavigate = e => e.transitionWhile(Promise.reject(), { scrollRestoration: "after-transition" });
+  navigation.onnavigate =
+      e => e.intercept({ handler: () => Promise.reject(),
+                         scrollRestoration: "after-transition" });
 
   await promise_rejects_exactly(t, undefined, navigation.back().finished);
   assert_not_equals(window.scrollY, 0);
-}, "scrollRestoration: after-transition should not scroll when the transitionWhile promise rejects");
+}, "scrollRestoration: after-transition should not scroll when the intercept() handler rejects");
 </script>
 </body>
diff --git a/testing/web-platform/tests/navigation-api/scroll-restoration/after-transition-timing.html b/testing/web-platform/tests/navigation-api/scroll-restoration/after-transition-timing.html
index 35a9071459f7c..3bb892054aab6 100644
--- a/testing/web-platform/tests/navigation-api/scroll-restoration/after-transition-timing.html
+++ b/testing/web-platform/tests/navigation-api/scroll-restoration/after-transition-timing.html
@@ -13,12 +13,6 @@
   await navigation.navigate("#frag").finished;
   assert_not_equals(window.scrollY, 0);
 
-  let transitionWhile_resolve;
-  navigation.onnavigate = t.step_func(e => {
-    e.transitionWhile(new Promise(r => transitionWhile_resolve = r));
-    assert_not_equals(window.scrollY, 0);
-  }), { scrollRestoration: "after-transition" };
-
   window.onpopstate = t.step_func(() => assert_not_equals(window.scrollY, 0));
   window.onhashchange = t.step_func(() => assert_not_equals(window.scrollY, 0));
 
@@ -30,10 +24,21 @@
   });
 
   let back_promises = navigation.back();
-
-  await back_promises.committed;
-  transitionWhile_resolve();
-  assert_not_equals(window.scrollY, 0);
+  navigation.onnavigate = t.step_func(e => {
+    e.intercept({ scrollRestoration: "after-transition",
+                  handler: async () => {
+                    // The ordering here should be:
+                    //  * intercept() is called
+                    //  * back_promises.committed is resolved
+                    //  * this handler runs.
+                    // If this handler incorrectly blocks back_promises.committed,
+                    // this test will hang.
+                    await back_promises.committed;
+                    assert_not_equals(window.scrollY, 0);
+                  }
+                });
+    assert_not_equals(window.scrollY, 0);
+  });
 
   await back_promises.finished;
   assert_equals(window.scrollY, 0);
diff --git a/testing/web-platform/tests/navigation-api/scroll-restoration/after-transition-with-history-scroll-restoration-manual.html b/testing/web-platform/tests/navigation-api/scroll-restoration/after-transition-with-history-scroll-restoration-manual.html
index 6c7a8385606ee..90dfebd68bf85 100644
--- a/testing/web-platform/tests/navigation-api/scroll-restoration/after-transition-with-history-scroll-restoration-manual.html
+++ b/testing/web-platform/tests/navigation-api/scroll-restoration/after-transition-with-history-scroll-restoration-manual.html
@@ -15,7 +15,7 @@
   await navigation.navigate("#frag").finished;
   assert_not_equals(window.scrollY, 0);
 
-  navigation.onnavigate = e => e.transitionWhile(Promise.resolve(), { scrollRestoration: "after-transition" });
+  navigation.onnavigate = e => e.intercept({ scrollRestoration: "after-transition" });
   await navigation.back().finished;
   assert_equals(window.scrollY, 0);
 }, "scrollRestoration: after-transition should ignore history.scrollRestoration");
diff --git a/testing/web-platform/tests/navigation-api/scroll-restoration/manual-basic.html b/testing/web-platform/tests/navigation-api/scroll-restoration/manual-basic.html
index 84732fb532bd2..5421cd66ae6ff 100644
--- a/testing/web-platform/tests/navigation-api/scroll-restoration/manual-basic.html
+++ b/testing/web-platform/tests/navigation-api/scroll-restoration/manual-basic.html
@@ -12,7 +12,7 @@
   assert_equals(window.scrollY, 0);
   await navigation.navigate("#frag").finished;
   assert_not_equals(window.scrollY, 0);
-  navigation.onnavigate = e => e.transitionWhile(Promise.resolve(), { scrollRestoration: "manual" });
+  navigation.onnavigate = e => e.intercept({ scrollRestoration: "manual" });
   await navigation.back().finished;
   assert_not_equals(window.scrollY, 0);
 }, "scrollRestoration: manual should prevent auto scroll on back.");
diff --git a/testing/web-platform/tests/navigation-api/scroll-restoration/manual-immediate-restoreScroll.html b/testing/web-platform/tests/navigation-api/scroll-restoration/manual-immediate-restoreScroll.html
index f0676ea1b3787..c35a77e57d45a 100644
--- a/testing/web-platform/tests/navigation-api/scroll-restoration/manual-immediate-restoreScroll.html
+++ b/testing/web-platform/tests/navigation-api/scroll-restoration/manual-immediate-restoreScroll.html
@@ -13,7 +13,7 @@
   await navigation.navigate("#frag").finished;
   assert_not_equals(window.scrollY, 0);
   navigation.onnavigate = e => {
-    e.transitionWhile(Promise.resolve(), { scrollRestoration: "manual" });
+    e.intercept({ scrollRestoration: "manual" });
     e.restoreScroll();
     assert_equals(window.scrollY, 0);
   }
diff --git a/testing/web-platform/tests/navigation-api/scroll-restoration/manual-restoreScroll-after-dispatch.html b/testing/web-platform/tests/navigation-api/scroll-restoration/manual-restoreScroll-after-dispatch.html
index a3d01a52a34f8..4ebc08eb71495 100644
--- a/testing/web-platform/tests/navigation-api/scroll-restoration/manual-restoreScroll-after-dispatch.html
+++ b/testing/web-platform/tests/navigation-api/scroll-restoration/manual-restoreScroll-after-dispatch.html
@@ -13,18 +13,19 @@
   await navigation.navigate("#frag").finished;
   assert_not_equals(window.scrollY, 0);
 
-  let transitionWhile_resolve;
+  let intercept_resolve;
   let navigate_event;
   navigation.onnavigate = e => {
     navigate_event = e;
-    e.transitionWhile(new Promise(r => transitionWhile_resolve = r), { scrollRestoration: "manual" });
+    e.intercept({ handler: () => new Promise(r => intercept_resolve = r),
+                  scrollRestoration: "manual" });
   };
   let back_promises = navigation.back();
   await back_promises.committed;
   assert_not_equals(window.scrollY, 0);
   navigate_event.restoreScroll();
   assert_equals(window.scrollY, 0);
-  transitionWhile_resolve();
+  intercept_resolve();
   await back_promises.finished;
   assert_equals(window.scrollY, 0);
 }, "scrollRestoration: restoreScroll() should work after a navigate event dispatch");
diff --git a/testing/web-platform/tests/navigation-api/scroll-restoration/manual-restoreScroll-after-resolve.html b/testing/web-platform/tests/navigation-api/scroll-restoration/manual-restoreScroll-after-resolve.html
index 6cf0fe16061e7..6a98638ffdd54 100644
--- a/testing/web-platform/tests/navigation-api/scroll-restoration/manual-restoreScroll-after-resolve.html
+++ b/testing/web-platform/tests/navigation-api/scroll-restoration/manual-restoreScroll-after-resolve.html
@@ -16,7 +16,7 @@
   let navigate_event;
   navigation.onnavigate = e => {
     navigate_event = e;
-    e.transitionWhile(Promise.resolve(), { scrollRestoration: "manual" });
+    e.intercept({ scrollRestoration: "manual" });
   };
   await navigation.back().finished;
   assert_not_equals(window.scrollY, 0);
diff --git a/testing/web-platform/tests/navigation-api/scroll-restoration/manual-restoreScroll-repeated.html b/testing/web-platform/tests/navigation-api/scroll-restoration/manual-restoreScroll-repeated.html
index 9ca5bfa064345..f29f533fe07ce 100644
--- a/testing/web-platform/tests/navigation-api/scroll-restoration/manual-restoreScroll-repeated.html
+++ b/testing/web-platform/tests/navigation-api/scroll-restoration/manual-restoreScroll-repeated.html
@@ -13,7 +13,7 @@
   await navigation.navigate("#frag").finished;
   assert_not_equals(window.scrollY, 0);
   navigation.onnavigate = t.step_func(e => {
-    e.transitionWhile(Promise.resolve(), { scrollRestoration: "manual" });
+    e.intercept({ scrollRestoration: "manual" });
     e.restoreScroll();
     assert_equals(window.scrollY, 0);
     assert_throws_dom("InvalidStateError", () => e.restoreScroll());
diff --git a/testing/web-platform/tests/navigation-api/scroll-restoration/restoreScroll-exceptions.html b/testing/web-platform/tests/navigation-api/scroll-restoration/restoreScroll-exceptions.html
index 2f2b459d93bd9..0b9ff28d751a8 100644
--- a/testing/web-platform/tests/navigation-api/scroll-restoration/restoreScroll-exceptions.html
+++ b/testing/web-platform/tests/navigation-api/scroll-restoration/restoreScroll-exceptions.html
@@ -12,27 +12,27 @@
 
   // Throw for non-traverse
   navigation.addEventListener("navigate", t.step_func(e => {
-    e.transitionWhile(Promise.resolve());
+    e.intercept();
     assert_throws_dom("InvalidStateError", () => e.restoreScroll());
   }), { once : true });
   await navigation.navigate("#frag").finished;
 
-  // Throw for non-transitionWhile() traverse
+  // Throw for non-intercept() traverse
   navigation.addEventListener("navigate", t.step_func(e => {
     assert_throws_dom("InvalidStateError", () => e.restoreScroll());
   }), { once : true });
   await navigation.back().finished;
 
-  // Throw for transitionWhile() traverse with no explicit scrollRestoration behavior.
+  // Throw for intercept() traverse with no explicit scrollRestoration behavior.
   navigation.addEventListener("navigate", t.step_func(e => {
-    e.transitionWhile(Promise.resolve());
+    e.intercept();
     assert_throws_dom("InvalidStateError", () => e.restoreScroll());
   }), { once : true });
   await navigation.forward().finished;
 
-  // Throw for transitionWhile() traverse with scrollRestoration "after-transition".
+  // Throw for intercept() traverse with scrollRestoration "after-transition".
   navigation.addEventListener("navigate", t.step_func(e => {
-    e.transitionWhile(Promise.resolve(), { scrollRestoration: "after-transition" });
+    e.intercept({ scrollRestoration: "after-transition" });
     assert_throws_dom("InvalidStateError", () => e.restoreScroll());
   }), { once : true });
   await navigation.back().finished;