手写Promise 手写Promise

如何使用promise

const p1 = new Promise((resolve, reject) = { 执行一个任务成功了调用resolve() 失败了调用reject() })

p1.then(s1, e1)

当调用resolve()之后会调用s1
【手写Promise】当失败了调用reject()会调用e1
手写Promise

class Promise2 { quene1 = [] quene2 = []constructor(fn) { const resolve = (data) => { setTimeout(() => { for (let i = 0; i <= quene1.length; i++) { this.quene1[i](data) } }) } const reject = (data) => { setTimeout(() => { for (let i = 0; i <= this.quene2.length; i++) { this.quene2[i](data) } }) } fn(resolve, reject) }then(s, e) { this.quene1.push(s) this.quene2.push(e) return this } }