易理解的Promise封装

//promise英文中叫做承诺
//成功resolve  失败reject 正在过程中 pending 没人接的时候


var obj = {
    status: '',
    value: ''
}
function Apromise(fn) {
    obj.status = 'pending'
    obj.value = ''
    function resolve(value) {
        if (obj.status === 'pending') {
            obj.status = 'resolve'
            obj.value = value
        }
    }
    function reject(value) {
        if (obj.status === 'pending') {
            obj.status = 'reject'
            obj.value = value
            console.log(456456);
        }
    }
    console.log(123123);
    fn(resolve, reject)
}
Apromise.prototype.then = function (resolve, reject) {
    if (obj.status === 'resolve') {
        resolve(obj.value)
    }
    if (obj.status === 'reject') {
        reject(obj.value)
    }
}
let p = new Apromise((resolve, reject) => {
    //resolve('1')
    reject('2')
}).then(res => {
    console.log(res)
}, err => {
    console.log(err)
})

实例化promise：相当于如果有成功的条件就把function Apromise中的成功函数放到最下面进行执行
.then：相当于把then中的函数放入Apromise.prototype.then中进行根据之前设置的状态执行输出(obj.value)

总结 没看源码现在感觉就是形参实参的来回调用 没啥的