实现promise、call、apply、bind_promise.apply

实现promise、call、apply、bind

下面直接上代码，实现分析实现promise、call、apply、bind原理实现,如有问题欢迎指点。

// prmoise实现
const PENDING = 'pending'
const RESOLVED = 'resolved'
const REJECTED = 'rejected'

function MyPromise(fn) {
   
    const that = this
    that.state = PENDING
    that.value = null
    that.resolvedCallbacks = []
    that.rejectedCallbacks = []
    // 待完善resolve和reject函数
    // 待完善fn执行函数
}

function resolve(value) {
   
    const that = this
    if (that.state === PENDING) {
   
        that.state = RESOLVED
        that.value = value
        that.resolvedCallbacks.map(cb => cb(thst.value))
    }
}

function reject(value) {
   
    const that = this
    if (that.state ===
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