From: Evan You <yyx990803@gmail.com>
Date: Mon, 19 Oct 2020 21:37:10 +0000 (-0400)
Subject: fix(reactivity): track length on for in iteration on Array
X-Git-Tag: v3.0.2~12
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=0e5a3c47a7398dfd0107fccf9b615772dd01aa74;p=thirdparty%2Fvuejs%2Fcore.git

fix(reactivity): track length on for in iteration on Array

fix #2427
---

diff --git a/packages/reactivity/__tests__/reactiveArray.spec.ts b/packages/reactivity/__tests__/reactiveArray.spec.ts
index 170cb1b39c..da3dc1f101 100644
--- a/packages/reactivity/__tests__/reactiveArray.spec.ts
+++ b/packages/reactivity/__tests__/reactiveArray.spec.ts
@@ -128,6 +128,21 @@ describe('reactivity/reactive/Array', () => {
     expect(fn).toHaveBeenCalledTimes(1)
   })
 
+  // #2427
+  test('track length on for ... in iteration', () => {
+    const array = reactive([1])
+    let length = ''
+    effect(() => {
+      length = ''
+      for (const key in array) {
+        length += key
+      }
+    })
+    expect(length).toBe('0')
+    array.push(1)
+    expect(length).toBe('01')
+  })
+
   describe('Array methods w/ refs', () => {
     let original: any[]
     beforeEach(() => {
diff --git a/packages/reactivity/src/baseHandlers.ts b/packages/reactivity/src/baseHandlers.ts
index 3d5ee55f62..a246b6f319 100644
--- a/packages/reactivity/src/baseHandlers.ts
+++ b/packages/reactivity/src/baseHandlers.ts
@@ -179,7 +179,7 @@ function has(target: object, key: string | symbol): boolean {
 }
 
 function ownKeys(target: object): (string | number | symbol)[] {
-  track(target, TrackOpTypes.ITERATE, ITERATE_KEY)
+  track(target, TrackOpTypes.ITERATE, isArray(target) ? 'length' : ITERATE_KEY)
   return Reflect.ownKeys(target)
 }