fix: correct documentation for beforeNavigate (#11300)

* changeset

* lint

* regenerate types

---------

Co-authored-by: Rich Harris <rich.harris@vercel.com>

.changeset/violet-rockets-smoke.md

@@ -0,0 +1,5 @@
+---
+'@sveltejs/kit': patch
+---
+
+fix: correct documentation for beforeNavigate

packages/kit/src/runtime/app/navigation.js

@@ -89,10 +89,12 @@ export const preloadCode = /* @__PURE__ */ client_method('preload_code');
 
 /**
  * A navigation interceptor that triggers before we navigate to a new URL, whether by clicking a link, calling `goto(...)`, or using the browser back/forward controls.
- * Calling `cancel()` will prevent the navigation from completing. If the navigation would have directly unloaded the current page, calling `cancel` will trigger the native
- * browser unload confirmation dialog. In these cases, `navigation.willUnload` is `true`.
  *
- * When a navigation isn't client side, `navigation.to.route.id` will be `null`.
+ * Calling `cancel()` will prevent the navigation from completing. If `navigation.type === 'leave'` — meaning the user is navigating away from the app (or closing the tab) — calling `cancel` will trigger the native browser unload confirmation dialog. In this case, the navigation may or may not be cancelled depending on the user's response.
+ *
+ * When a navigation isn't to a SvelteKit-owned route (and therefore controlled by SvelteKit's client-side router), `navigation.to.route.id` will be `null`.
+ *
+ * If the navigation will (if not cancelled) cause the document to unload — in other words `'leave'` navigations and `'link'` navigations where `navigation.to.route === null` — `navigation.willUnload` is `true`.
  *
  * `beforeNavigate` must be called during a component initialization. It remains active as long as the component is mounted.
  * @type {(callback: (navigation: import('@sveltejs/kit').BeforeNavigate) => void) => void}

packages/kit/types/index.d.ts

@@ -1972,10 +1972,12 @@ declare module '$app/navigation' {
 	export const preloadCode: (...urls: string[]) => Promise<void>;
 	/**
 	 * A navigation interceptor that triggers before we navigate to a new URL, whether by clicking a link, calling `goto(...)`, or using the browser back/forward controls.
-	 * Calling `cancel()` will prevent the navigation from completing. If the navigation would have directly unloaded the current page, calling `cancel` will trigger the native
-	 * browser unload confirmation dialog. In these cases, `navigation.willUnload` is `true`.
 	 *
-	 * When a navigation isn't client side, `navigation.to.route.id` will be `null`.
+	 * Calling `cancel()` will prevent the navigation from completing. If `navigation.type === 'leave'` — meaning the user is navigating away from the app (or closing the tab) — calling `cancel` will trigger the native browser unload confirmation dialog. In this case, the navigation may or may not be cancelled depending on the user's response.
+	 *
+	 * When a navigation isn't to a SvelteKit-owned route (and therefore controlled by SvelteKit's client-side router), `navigation.to.route.id` will be `null`.
+	 *
+	 * If the navigation will (if not cancelled) cause the document to unload — in other words `'leave'` navigations and `'link'` navigations where `navigation.to.route === null` — `navigation.willUnload` is `true`.
 	 *
 	 * `beforeNavigate` must be called during a component initialization. It remains active as long as the component is mounted.
 	 * */