SOURCE

const promise = new Promise((resolve, reject) => {
    console.log('第一步1')
    resolve('第一步')
    reject('失败')
})

promise.then(
    (result) => { console.log(`正确回调：${result}`) },
    (reason) => { console.log(`错误回调：${reason}`) }
)

class MyPromise {
    static PENDING = '待定';
    static FULFILL = '成功';
    static REJECTED = '拒绝'

    constructor(exec) {
        this.status = MyPromise.PENDING
        exec(this.resolve,this.reject)
    }

    resolve(){

    }
    
    reject(){

    }
}

const myPromise = new MyPromise((resolve,reject) => {

})