// src/core/instance/stateexportfunctioninitState (vm: Component) {
vm._watchers = []
const opts = vm.$options
if (opts.props) initProps(vm, opts.props)
if (opts.methods) initMethods(vm, opts.methods)
if (opts.data) {
initData(vm)
} else {
observe(vm._data = {}, true/* asRootData */)
}
if (opts.computed) initComputed(vm, opts.computed)
if (opts.watch && opts.watch !== nativeWatch) {
initWatch(vm, opts.watch)
}
}
initData
initData核心代码是data数据响应化
functioninitData (vm: Component) {
let data = vm.$options.data
data = vm._data = typeof data === 'function'
? getData(data, vm)
: data || {}
// 把data代理到实例上const keys = Object.keys(data)
const props = vm.$options.props
const methods = vm.$options.methods
let i = keys.length
while (i--) {
const key = keys[i]
proxy(vm, `_data`, key)
}
// observe data
observe(data, true/* asRootData */)
}
observe
observe方法返回一个Observer实例
/**
* Attempt to create an observer instance for a value,
* returns the new observer if successfully observed,
* or the existing observer if the value already has one.
*/exportfunctionobserve (value: any, asRootData: ?boolean): Observer | void{
if (!isObject(value) || value instanceof VNode) {
return
}
let ob: Observer | voidif (hasOwn(value, '__ob__') && value.__ob__ instanceof Observer) {
ob = value.__ob__
} elseif (
shouldObserve &&
!isServerRendering() &&
(Array.isArray(value) || isPlainObject(value)) &&
Object.isExtensible(value) &&
!value._isVue
) {
ob = new Observer(value)
}
if (asRootData && ob) {
ob.vmCount++
}
return ob
}
Observer
Observer对象根据数据类型执行对应的响应化操作
/**
* Observer class that is attached to each observed
* object. Once attached, the observer converts the target
* object's property keys into getter/setters that
* collect dependencies and dispatch updates.
*/exportclassObserver{
value: any;
dep: Dep;// 保存数组类型数据的依赖
vmCount: number; // number of vms that have this object as root $dataconstructor (value: any) {
this.value = value
this.dep = new Dep()
this.vmCount = 0
def(value, '__ob__', this)
if (Array.isArray(value)) {
if (hasProto) {
protoAugment(value, arrayMethods)
} else {
copyAugment(value, arrayMethods, arrayKeys)
}
this.observeArray(value)
} else {
this.walk(value)
}
}
/**
* Walk through all properties and convert them into
* getter/setters. This method should only be called when
* value type is Object.
* 如果是对象，则执行该函数
*/
walk (obj: Object) {
const keys = Object.keys(obj)
for (let i = 0; i < keys.length; i++) {
defineReactive(obj, keys[i])
}
}
/**
* Observe a list of Array items.
*/
observeArray (items: Array<any>) {
for (let i = 0, l = items.length; i < l; i++) {
observe(items[i])
}
}
}
defineReactive
defineReactive定义对象的getter/setter
**
* Define a reactive property on an Object.
*/
export function defineReactive (
obj: Object,
key: string,
val: any,
customSetter?: ?Function,
shallow?: boolean
) {
const dep = new Dep()
const property = Object.getOwnPropertyDescriptor(obj, key)
if (property && property.configurable === false) {
return
}
// cater for pre-defined getter/setters
const getter = property && property.get
const setter = property && property.set
if ((!getter || setter) && arguments.length === 2) {
val = obj[key]
}
let childOb = !shallow && observe(val)
Object.defineProperty(obj, key, {
enumerable: true,
configurable: true,
get: function reactiveGetter () {
const value = getter ? getter.call(obj) : val
if (Dep.target) {
dep.depend()
if (childOb) {
childOb.dep.depend()
if (Array.isArray(value)) {
dependArray(value)
}
}
}
return value
},
set: function reactiveSetter (newVal) {
const value = getter ? getter.call(obj) : val
/* eslint-disable no-self-compare */
if (newVal === value || (newVal !== newVal && value !== value)) {
return
}
/* eslint-enable no-self-compare */
if (process.env.NODE_ENV !== 'production' && customSetter) {
customSetter()
}
// #7981: for accessor properties without setter
if (getter && !setter) return
if (setter) {
setter.call(obj, newVal)
} else {
val = newVal
}
childOb = !shallow && observe(newVal) // 递归子对象
dep.notify()
}
})
}
Dep
Dep负责管理一组Watcher,包括watcher实例的增删及通知更新
/**
* A dep is an observable that can have multiple
* directives subscribing to it.
*/exportdefaultclassDep{
static target: ?Watcher;
id: number;
subs: Array<Watcher>;
constructor () {
this.id = uid++
this.subs = []
}
addSub (sub: Watcher) {
this.subs.push(sub)
}
removeSub (sub: Watcher) {
remove(this.subs, sub)
}
// 调用watcher的adddep方法实现watcher和dep相互引用
depend () {
if (Dep.target) {
Dep.target.addDep(this)
}
}
notify () {
// stabilize the subscriber list firstconst subs = this.subs.slice()
for (let i = 0, l = subs.length; i < l; i++) {
subs[i].update()
}
}
}
// The current target watcher being evaluated.// This is globally unique because only one watcher// can be evaluated at a time.
Dep.target = null
