diff --git a/.vscode/launch.json b/.vscode/launch.json
index c4ffd0fc5c3..6a86d1c149e 100644
--- a/.vscode/launch.json
+++ b/.vscode/launch.json
@@ -19,7 +19,8 @@
         "NODE_ENV": "development"
       },
       "console": "integratedTerminal",
-      "sourceMaps": true
+      "sourceMaps": true,
+      "skipFiles": ["<node_internals>", "node_modules"]
     }
   ]
 }
diff --git a/packages/reactivity/src/effect.ts b/packages/reactivity/src/effect.ts
index 010aea0020a..6e1fd27893f 100644
--- a/packages/reactivity/src/effect.ts
+++ b/packages/reactivity/src/effect.ts
@@ -194,13 +194,14 @@ export function trigger(
       addRunners(effects, computedRunners, depsMap.get(key))
     }
     // also run for iteration key on ADD | DELETE | Map.SET
-    if (
-      type === TriggerOpTypes.ADD ||
+    if (type === TriggerOpTypes.ADD) {
+      const iterationKey = isArray(target) ? 'length' : ITERATE_KEY
+      addRunners(effects, computedRunners, depsMap.get(iterationKey))
+    } else if (
       type === TriggerOpTypes.DELETE ||
       (type === TriggerOpTypes.SET && target instanceof Map)
     ) {
-      const iterationKey = isArray(target) ? 'length' : ITERATE_KEY
-      addRunners(effects, computedRunners, depsMap.get(iterationKey))
+      addRunners(effects, computedRunners, depsMap.get(ITERATE_KEY))
     }
   }
   const run = (effect: ReactiveEffect) => {