SOURCE

let p1 = new Promise((resolve, reject) => {
    setTimeout(() => {
        resolve(1000)
    }, 4000)
})
let p2 = new Promise((resolve, reject) => {

    setTimeout(() => {
        resolve(2000)
    }, 3000)
})
let p3 = new Promise((resolve, reject) => {
    setTimeout(() => {
        reject(3000)
    }, 2000)
})
Promise.all([p1, p2, p3]).then(res => {
    console.log(res)
}).catch(err => {
    console.log(err, '--90')
})
Promise.race([p1, p2, p3]).then(res => {
    console.log(res)
})
Promise.allSettled([p1, p2, p3]).then(res => {
    console.log(res)
})
Promise.any([p1, p2, p3]).then(res => {
    console.log(res)
})
// 手写promise
class MyPromise {
    // 构造方法
    constructor(executor) {
        // 初始化值
        this.initValue()
        // 初始化this指向
        this.initBind()
        // 执行传进来的函数
        executor(this.resolve, this.reject)
    }

    initBind() {
        // 初始化this
        this.resolve = this.resolve.bind(this)
        this.reject = this.reject.bind(this)
    }

    initValue() {
        // 初始化值
        this.PromiseResult = null // 终值
        this.PromiseState = 'pending' // 状态
    }

    resolve(value) {
        // 如果执行resolve，状态变为fulfilled
        this.PromiseState = 'fulfilled'
        // 终值为传进来的值
        this.PromiseResult = value
    }

    reject(reason) {
        // 如果执行reject，状态变为rejected
        this.PromiseState = 'rejected'
        // 终值为传进来的reason
        this.PromiseResult = reason
    }
}