通过图带你深入了解vue的响应式原理

Object.defineProperty(obj, key, {
enumerable: true,
configurable: true,
get: function reactiveGetter () {
// ...
},
set: function reactiveSetter (newVal) {
// ...
}
})

// 在mount的生命钩子中
new Watcher(vm, updateComponent, noop, {
before () {
if (vm._isMounted && !vm._isDestroyed) {
callHook(vm, 'beforeUpdate')
}
}
}, true /* isRenderWatcher */)

<div id="app">
{{ message }}
{{ message1 }}
<input type="text" v-model="message">
<div @click="changeMessage">改变message</div> 
</div>

var app = new Vue({
el: '#app',
data: {
message: '1',
message1: '2',
},
methods: {
changeMessage() {
this.message = '2'
}
},
watch: {
message: function(val) {
this.message1 = val
}
}
})

get () {
pushTarget(this)
let value
const vm = this.vm
try {
value = this.getter.call(vm, vm)
} catch (e) {
// 省略
} finally {
if (this.deep) {
traverse(value)
}
popTarget()
this.cleanupDeps()
}
return value
}

Object.defineProperty(obj, key, {
enumerable: true,
configurable: true,
get: function reactiveGetter () {
const value = getter ? getter.call(obj) : val
if (Dep.target) {
dep.depend()
// ...
}
return value
},
set: function reactiveSetter (newVal) {
// ...
dep.notify()
}
})

depend () {
if (Dep.target) {
Dep.target.addDep(this)
}
}
addDep (dep: Dep) {
const id = dep.id
if (!this.newDepIds.has(id)) {
this.newDepIds.add(id)
this.newDeps.push(dep)
if (!this.depIds.has(id)) {
dep.addSub(this)
}
}
}

<div id="app">
{{ message }}
{{ message1 }}
<input type="text" v-model="message">
<div @click="changeMessage">改变message</div> 
</div>

var app = new Vue({
el: '#app',
data: {
message: '1',
message1: '2',
},
methods: {
changeMessage() {
this.message = '3'
}
},
watch: {
message: function(val) {
this.message1 = val
}
}
})

function queueWatcher (watcher) {
const id = watcher.id
if (has[id] == null) {
has[id] = true
queue.push(watcher)
// ...
if (!waiting) {
waiting = true
// ...
nextTick(flushSchedulerQueue)
}
}
}