手写Promise

```js const PENDING = 'pending' const FUFILLED = 'fulfilled' const REJECTED = 'rejected' class MyPro

```js const PENDING = 'pending' const FUFILLED = 'fulfilled' const REJECTED = 'rejected' class MyPro

```js // PromiseAll方法模拟 // 原PromiseAll演示 function p1 () { return new Promise((resolve, reject) => {

```js // then方法参数变成可选参数 // 原promise演示 var promise = new Promise((resolve, reject) => { resolve(100)

```js // promise的循环调用 // 错误示例 // const promise = new Promise((resolve, reject) => { // resolve(100)

```js // then链式调用 成功回调的返回值为promise对象时 const PENDING = 'pending' const FUFILLED = 'fulfilled' const R

```js // then链式调用 const PENDING = 'pending' const FUFILLED = 'fulfilled' const REJECTED = 'rejected'

```js // 处理多个then const PENDING = 'pending' const FUFILLED = 'fulfilled' const REJECTED = 'rejected'

```js // 基础promise实现上再处理异步情况处理 const PENDING = 'pending' const FUFILLED = 'fulfilled' const REJECTED

```js // 基础版本Promise实现 const PENDING = 'pending' const FUFILLED = 'fulfilled' const REJECTED = 'reje

```js // 核心逻辑 /** * 1.Promise 就是一个类 在执行这个类的时候 需要传递一个执行器进去 执行器会立即执行 * 2.Promise 中有三种状态 分别为 成功 -》fulfi