function Promise(executor){ //executor執(zhí)行器
let self = this;
self.status = 'pending'; //等待態(tài)
self.value = undefined; // 表示當前成功的值
self.reason = undefined; // 表示是失敗的值
function resolve(value){ // 成功的方法
if(self.status === 'pending'){
self.status = 'resolved';
self.value = value;
}
}
function reject(reason){ //失敗的方法
if(self.status === 'pending'){
self.status = 'rejected';
self.reason = reason;
}
}
executor(resolve,reject);
}
Promise.prototype.then = function(onFufiled,onRejected){
let self = this;
if(self.status === 'resolved'){
onFufiled(self.value);
}
if(self.status === 'rejected'){
onRejected(self.reason);
}
}
module.exports = Promise;
檢驗
et Promise = require('./Promise');
let promise = new Promise(function (resolve, reject) {
resolve(100);
})
promise.then(function (data) {
console.log('data:', data);
},function (err) {
console.log('err:', err);
})
輸出：data: 100
