From 9821998057efe1ca0d00da2fd0f2c71d0f61e05d Mon Sep 17 00:00:00 2001
From: guaijie <30885718+guaijie@users.noreply.github.com>
Date: Fri, 21 Feb 2020 23:08:44 +0800
Subject: [PATCH 1/3] fix(effect): optimize effect trigger

---
 packages/reactivity/src/effect.ts | 14 +++++++++++---
 1 file changed, 11 insertions(+), 3 deletions(-)

diff --git a/packages/reactivity/src/effect.ts b/packages/reactivity/src/effect.ts
index 03326426d81..acf6c195a4d 100644
--- a/packages/reactivity/src/effect.ts
+++ b/packages/reactivity/src/effect.ts
@@ -165,7 +165,8 @@ export function trigger(
   target: object,
   type: TriggerOpTypes,
   key?: unknown,
-  extraInfo?: DebuggerEventExtraInfo
+  extraInfo?: DebuggerEventExtraInfo,
+  newValue?: unknown
 ) {
   const depsMap = targetMap.get(target)
   if (depsMap === void 0) {
@@ -174,12 +175,19 @@ export function trigger(
   }
   const effects = new Set<ReactiveEffect>()
   const computedRunners = new Set<ReactiveEffect>()
-  if (type === TriggerOpTypes.CLEAR || (key === 'length' && isArray(target))) {
+  if (type === TriggerOpTypes.CLEAR) {
     // collection being cleared or Array length mutation
     // trigger all effects for target
-    depsMap.forEach(dep => {
+    depsMap.forEach((dep, i) => {
       addRunners(effects, computedRunners, dep)
     })
+  } else if (key === 'length' && isArray(target)) {
+    const startIndex: number = (newValue as number) || 0
+    depsMap.forEach((dep, i) => {
+      if (i >= startIndex || i === 'length') {
+        addRunners(effects, computedRunners, dep)
+      }
+    })
   } else {
     // schedule runs for SET | ADD | DELETE
     if (key !== void 0) {

From 67b724473f958ab895b8c079e54b9767dbbb48eb Mon Sep 17 00:00:00 2001
From: guaijie <30885718+guaijie@users.noreply.github.com>
Date: Fri, 21 Feb 2020 23:17:00 +0800
Subject: [PATCH 2/3] Update baseHandlers.ts

---
 packages/reactivity/src/baseHandlers.ts | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/packages/reactivity/src/baseHandlers.ts b/packages/reactivity/src/baseHandlers.ts
index 43b6df903bd..4615aaeab1c 100644
--- a/packages/reactivity/src/baseHandlers.ts
+++ b/packages/reactivity/src/baseHandlers.ts
@@ -101,9 +101,9 @@ function createSetter(isReadonly = false, shallow = false) {
         }
       } else {
         if (!hadKey) {
-          trigger(target, TriggerOpTypes.ADD, key)
+          trigger(target, TriggerOpTypes.ADD, key, { newValue: value })
         } else if (hasChanged(value, oldValue)) {
-          trigger(target, TriggerOpTypes.SET, key)
+          trigger(target, TriggerOpTypes.SET, key, { newValue: value })
         }
       }
     }

From c1f4077c2623b54fcd9a05dd10a455fb84ffd426 Mon Sep 17 00:00:00 2001
From: guaijie <30885718+guaijie@users.noreply.github.com>
Date: Fri, 21 Feb 2020 23:19:04 +0800
Subject: [PATCH 3/3] Update effect.ts

---
 packages/reactivity/src/effect.ts | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/packages/reactivity/src/effect.ts b/packages/reactivity/src/effect.ts
index acf6c195a4d..0cfa2202e4b 100644
--- a/packages/reactivity/src/effect.ts
+++ b/packages/reactivity/src/effect.ts
@@ -165,8 +165,7 @@ export function trigger(
   target: object,
   type: TriggerOpTypes,
   key?: unknown,
-  extraInfo?: DebuggerEventExtraInfo,
-  newValue?: unknown
+  extraInfo?: DebuggerEventExtraInfo
 ) {
   const depsMap = targetMap.get(target)
   if (depsMap === void 0) {
@@ -182,6 +181,7 @@ export function trigger(
       addRunners(effects, computedRunners, dep)
     })
   } else if (key === 'length' && isArray(target)) {
+    const newValue = extraInfo.newValue
     const startIndex: number = (newValue as number) || 0
     depsMap.forEach((dep, i) => {
       if (i >= startIndex || i === 'length') {