手写Promise

手写Promise的规范手册promisesaplus官网

链接: 官网链接

手写Promise-结构的设计

// 手写Promsie
const PROMISE_STATUS_PENDING = 'pending' //等待状态
const PROMISE_STATUS_FULFILLED = 'fulfilled' //完成状态
const PROMISE_STATUS_REJECTED = 'rejected' //拒绝/失败状态

class HyPromise{
    constructor(excutor){
        this.statu = PROMISE_STATUS_PENDING
        this.value = undefined
        this.reason = undefined
        const resolve = (value) => {
            if(this.statu  === PROMISE_STATUS_PENDING){
                this.statu = PROMISE_STATUS_FULFILLED
                this.value = value
                console.log('resolve函数调用了');
            }
        }
        
        const reject = (reason) => {
            if(this.statu === PROMISE_STATUS_PENDING){
                this.statu = PROMISE_STATUS_REJECTED
                this.reason = reason
                console.log('reject函数调用了');
            }
        }
        excutor(resolve,reject)
    }
}

const promise = new HyPromise((resolve,reject) => {
    console.log('执行者函数调用');
    reject('1111111');
    resolve();
})

promise.then(res => {
    
}).catch(err => {

})