vue.js 原始碼學習筆記 ----- Dep

標籤：default   ted   first   push   rom   cto   logs   ack   uid   

/* @flow */import type Watcher from ‘./watcher‘import { remove } from ‘../util/index‘let uid = 0/** * A dep is an observable that can have multiple * directives subscribing to it.
    */export default class Dep {  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)  }  depend () {    if (Dep.target) {      Dep.target.addDep(this)    }  }  notify () {    // stabilize the subscriber list first , 避免改動影響到原來的數組    const 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 there could be only one// watcher being evaluated at any time.Dep.target = nullconst targetStack = []export function pushTarget (_target: Watcher) {  if (Dep.target) targetStack.push(Dep.target)  Dep.target = _target}export function popTarget () {  Dep.target = targetStack.pop()}

 

vue.js 原始碼學習筆記 ----- Dep