promise是es6推出实用于异步申请的构造函数，帮忙解决回调天堂的问题，以下内容将自定义实现promise，只包含根本应用，所以一些边界状况思考没有在内。
如果对promise用法还不相熟的敌人可移步
Promise的了解与应用(一)
Promise的了解和应用(二)
executor
首先建设promise的根本构造
定义构造函数
promise的executor局部是放到主线程中间接执行的
class icePromise { constructor(executor){ const resolve = () => { console.log('resolve被调用') } const reject = () => { console.log('reject被调用') } } executor(resolve, reject)}const promise = new icePromise((resolve, reject)=>{ resolve()})定义状态
1、定义常量
const STATUS_PENDING = 'pending'const STATUS_FULFILLED = 'fulfilled'const STATUS_REJECTED = 'rejected'2、通过构造函数创立实例时，就应该须要状态，所以在类中定义
this.status = STATUS_PENDING 3、resolve和reject办法里通过状态判断
当为pending时，能力执行resolve或者reject办法，执行前先批改状态
then办法
onFulfilled/onRejected中要执行then外面的回调函数，将两个函数绑定到实例的属性上
1、在类中定义一个then办法
then(onFulfilled, onRejected){ this.onFulfilled = onFulfilled this.onRejected = onRejected}2、在resolve和reject中别离执行this.onFulfilled和this.onRejected中
此时会报错，因为executor会立即执行，而then外面的函数是微工作，
会在主线程执行实现之后执行
3、resolve和reject中退出 queueMicrotask (微工作)
整体架构的初版就实现了
const STATUS_PENDING = "pending";const STATUS_FULFILLED = "fulfilled";const STATUS_REJECTED = "rejected";class IcePromise { constructor(executor) { this.status = STATUS_PENDING; const resolve = (value) => { if (this.status === STATUS_PENDING) { this.status = STATUS_FULFILLED; queueMicrotask(() => { this.onFulfilled(value); }); } }; const reject = (reason) => { if (this.status === STATUS_PENDING) { this.status = STATUS_REJECTED; queueMicrotask(() => { this.onRejected(reason); }); } }; executor(resolve, reject); } then(onFulfilled, onRejected) { this.onFulfilled = onFulfilled; this.onRejected = onRejected; }}const promise = new IcePromise((resolve, reject) => { resolve("resolve"); reject("reject");});promise.then( (value) => { console.log("success1", value); }, (reason) => { console.log("fail1", reason); });promise.then( (value) => { console.log("success2", value); }, (reason) => { console.log("fail2", reason); });返回两次promise的状态，只执行第一个resolve，then办法中对应执行的胜利或者失败的函数也正确
但存在的问题是，执行两次then办法，只执行了第二个，以下对then办法进行优化。
then
解决屡次调用then办法的问题
1、constructor中定义变量用于收集所有的胜利/失败的回调函数
this.onFulfilledCallbacks = []this.onRejectedCallbacks = []2、 在then办法中通过push增加到数组中
this.onFulfilledCallbacks.push()this.onRejectedCallbacks.push()3、在resolve和reject中遍历
this.onFulfilledCallbacks和this.onRejectedCallbacks中的办法
此时代码如下
const STATUS_PENDING = "pending";const STATUS_FULFILLED = "fulfilled";const STATUS_REJECTED = "rejected";class IcePromise { constructor(executor) { this.status = STATUS_PENDING; this.onResolvedCallbacks = []; this.onRejectedCallbacks = []; const resolve = (value) => { if (this.status === STATUS_PENDING) { queueMicrotask(() => { this.onResolvedCallbacks.forEach((fn) => { fn(value); }); }); } }; const reject = (reason) => { if (this.status === STATUS_PENDING) { queueMicrotask(() => { this.onRejectedCallbacks.forEach((fn) => { fn(reason); }); }); } }; executor(resolve, reject); } then(onFulfilled, onRejected) { this.onResolvedCallbacks.push(onFulfilled); this.onRejectedCallbacks.push(onRejected); }}// 测试代码const promise = new IcePromise((resolve, reject) => { resolve("resolve---"); reject("----reject");});promise.then( (value) => { console.log("res1", value); }, (reason) => { console.log("err1", reason); })promise.then( (value) => { console.log("res2", value); }, (reason) => { console.log("err2", reason); });// 确定状态后再调用setTimeout(() => { promise.then( (res) => { console.log("res3", res); }, (err) => { console.log("err3", err); } );}, 1000);解决then的屡次调用的问题，但仍有其它的问题，一个是resolve和reject办法同时执行，二是通过定时器提早执行的promise的then办法没有输入响应后果
解决提早调用的问题
1、保留value和reason
this.value = undefinedthis.reason = undefinedresolve和reject办法别离给this.value和this.reason赋值
2、then办法中进行状态的判断
当状态为pending时，持续向onFulfilledCallbacks、onRejectedCallbacks数组中增加函数；当状态不为pending时，间接执行onFulfilled或onRejected办法
if (this.status === STATUS_FULFILLED && onFulfilled) { onFulfilled(this.value);}if (this.status === STATUS_REJECTED && onRejected) { onRejected(this.reason);}if (this.status === STATUS_PENDING) { this.onResolvedCallbacks.push(onFulfilled); this.onRejectedCallbacks.push(onRejected);}3、pending状态的变动
① queueMicrotask中判断不为pending则return
② 批改pending状态
const STATUS_PENDING = "pending";const STATUS_FULFILLED = "fulfilled";const STATUS_REJECTED = "rejected";class IcePromise { constructor(executor) { this.status = STATUS_PENDING; this.onResolvedCallbacks = []; this.onRejectedCallbacks = []; this.value = undefined; this.reason = undefined; const resolve = (value) => { if (this.status === STATUS_PENDING) { queueMicrotask(() => { if (this.status !== STATUS_PENDING) return; this.status = STATUS_FULFILLED; this.value = value; this.onResolvedCallbacks.forEach((fn) => { fn(this.value); }); }); } }; const reject = (reason) => { if (this.status === STATUS_PENDING) { queueMicrotask(() => { if (this.status !== STATUS_PENDING) return; this.status = STATUS_REJECTED; this.reason = reason; this.onRejectedCallbacks.forEach((fn) => { fn(this.reason); }); }); } }; executor(resolve, reject); } then(onFulfilled, onRejected) { if (this.status === STATUS_FULFILLED && onFulfilled) { onFulfilled(this.value); } if (this.status === STATUS_REJECTED && onRejected) { onRejected(this.reason); } if (this.status === STATUS_PENDING) { this.onResolvedCallbacks.push(onFulfilled); this.onRejectedCallbacks.push(onRejected); } }}// 测试代码const promise = new IcePromise((resolve, reject) => { resolve("resolve---"); reject("----reject");});promise.then( (value) => { console.log("res1", value); }, (reason) => { console.log("err1", reason); })promise.then( (value) => { console.log("res2", value); }, (reason) => { console.log("err2", reason); });// 确定状态后再调用setTimeout(() => { promise.then( (res) => { console.log("res3", res); }, (err) => { console.log("err3", err); } );}, 1000);promise.then( (value) => { console.log("res4", value); }, (reason) => { console.log("err4", reason); }).then( (value) => { console.log("res5", value); }, (reason) => { console.log("err5", reason); })解决了resolve和reject屡次调用及计时器提早调用的问题，但此时发现then无奈进行链式调用
解决链式调用的问题
1、then办法里返回一个 new icePromise，将判断逻辑放进去
2、this.onFulfilledCallbacks 和 this.onRejectedCallbacks 传入回调函数，
回调函数返回resolve或者reject函数的执行后果
3、封装工具函数，用于解决try catch
const STATUS_PENDING = "pending";const STATUS_FULFILLED = "fulfilled";const STATUS_REJECTED = "rejected";const respondWithCatchError = (fn, value, resolve, reject) => { try { const result = fn(value); resolve(result); } catch (error) { reject(error); }};class IcePromise { constructor(executor) { this.status = STATUS_PENDING; this.onResolvedCallbacks = []; this.onRejectedCallbacks = []; this.value = undefined; this.reason = undefined; const resolve = (value) => { if (this.status === STATUS_PENDING) { queueMicrotask(() => { if (this.status !== STATUS_PENDING) return; this.status = STATUS_FULFILLED; this.value = value; this.onResolvedCallbacks.forEach((fn) => { fn(this.value); }); }); } }; const reject = (reason) => { if (this.status === STATUS_PENDING) { queueMicrotask(() => { if (this.status !== STATUS_PENDING) return; this.status = STATUS_REJECTED; this.reason = reason; this.onRejectedCallbacks.forEach((fn) => { fn(this.reason); }); }); } }; executor(resolve, reject); } then(onFulfilled, onRejected) { return new Promise((resolve, reject) => { if (this.status === STATUS_FULFILLED && onFulfilled) { respondWithCatchError(onFulfilled, this.value, resolve, reject); } if (this.status === STATUS_REJECTED && onRejected) { respondWithCatchError(onRejected, this.reason, resolve, reject); } if (this.status === STATUS_PENDING) { this.onResolvedCallbacks.push(() => { respondWithCatchError(onFulfilled, this.value, resolve, reject); }); this.onRejectedCallbacks.push(() => { respondWithCatchError(onRejected, this.reason, resolve, reject); }); } }); }}// 测试代码const promise = new IcePromise((resolve, reject) => { resolve("resolve---"); reject("----reject");});promise .then( (value) => { console.log("res1", value); }, (reason) => { console.log("err1", reason); } ) .then( (value) => { console.log("res2", value); }, (reason) => { console.log("err2", reason); } ) .then( (res) => { console.log("res3", res); }, (err) => { console.log("err3", err); } );此时then函数就曾经能够链式调用啦，基本功能曾经实现~
catch
catch函数接管一个失败的回调
1、调用then办法，将onRejected办法加到第二个promise的回调中
catch(onRejected){ this.then(null, onRejected)}2、then办法中对传入的 onRejected进行判断，当没有传递时，就抛出异样
const defaultOnRejected = (reason) => { throw reason;};onRejected = onRejected || defaultOnRejected;整体实现如下
const STATUS_PENDING = "pending";const STATUS_FULFILLED = "fulfilled";const STATUS_REJECTED = "rejected";const respondWithCatchError = (fn, value, resolve, reject) => { try { const result = fn(value); resolve(result); } catch (error) { reject(error); }};class IcePromise { constructor(executor) { this.status = STATUS_PENDING; this.onResolvedCallbacks = []; this.onRejectedCallbacks = []; this.value = undefined; this.reason = undefined; const resolve = (value) => { if (this.status === STATUS_PENDING) { queueMicrotask(() => { if (this.status !== STATUS_PENDING) return; this.status = STATUS_FULFILLED; this.value = value; this.onResolvedCallbacks.forEach((fn) => { fn(this.value); }); }); } }; const reject = (reason) => { if (this.status === STATUS_PENDING) { queueMicrotask(() => { if (this.status !== STATUS_PENDING) return; this.status = STATUS_REJECTED; this.reason = reason; this.onRejectedCallbacks.forEach((fn) => { fn(this.reason); }); }); } }; executor(resolve, reject); } then(onFulfilled, onRejected) { const defaultOnFulfilled = (value) => { return value; }; const defaultOnRejected = (reason) => { throw reason; }; onFulfilled = onFulfilled || defaultOnFulfilled; onRejected = onRejected || defaultOnRejected; return new Promise((resolve, reject) => { if (this.status === STATUS_FULFILLED && onFulfilled) { respondWithCatchError(onFulfilled, this.value, resolve, reject); } if (this.status === STATUS_REJECTED && onRejected) { respondWithCatchError(onRejected, this.reason, resolve, reject); } if (this.status === STATUS_PENDING) { this.onResolvedCallbacks.push(() => { respondWithCatchError(onFulfilled, this.value, resolve, reject); }); this.onRejectedCallbacks.push(() => { respondWithCatchError(onRejected, this.reason, resolve, reject); }); } }); } catch(onRejected) { this.then(null, onRejected); }}const promise = new IcePromise((resolve, reject) => { reject("----reject"); resolve("resolve---");});// 测试代码promise .then((value) => { console.log("res1", value); }) .then((value) => { console.log("res2", value); }) .catch((error) => { console.log("catch", error); });执行后果如下
finally
finally办法无论执行resolve或者reject的办法后都会执行
finally(onFinally){ this.then(()=>{ onFinally() }, ()=>{ onFinally() })}整体实现如下
const STATUS_PENDING = "pending";const STATUS_FULFILLED = "fulfilled";const STATUS_REJECTED = "rejected";const respondWithCatchError = (fn, value, resolve, reject) => { try { const result = fn(value); resolve(result); } catch (error) { reject(error); }};class IcePromise { constructor(executor) { this.status = STATUS_PENDING; this.onResolvedCallbacks = []; this.onRejectedCallbacks = []; this.value = undefined; this.reason = undefined; const resolve = (value) => { if (this.status === STATUS_PENDING) { queueMicrotask(() => { if (this.status !== STATUS_PENDING) return; this.status = STATUS_FULFILLED; this.value = value; this.onResolvedCallbacks.forEach((fn) => { fn(this.value); }); }); } }; const reject = (reason) => { if (this.status === STATUS_PENDING) { queueMicrotask(() => { if (this.status !== STATUS_PENDING) return; this.status = STATUS_REJECTED; this.reason = reason; this.onRejectedCallbacks.forEach((fn) => { fn(this.reason); }); }); } }; executor(resolve, reject); } then(onFulfilled, onRejected) { const defaultOnFulfilled = (value) => { return value; }; const defaultOnRejected = (reason) => { throw reason; }; onFulfilled = onFulfilled || defaultOnFulfilled; onRejected = onRejected || defaultOnRejected; return new Promise((resolve, reject) => { if (this.status === STATUS_FULFILLED && onFulfilled) { respondWithCatchError(onFulfilled, this.value, resolve, reject); } if (this.status === STATUS_REJECTED && onRejected) { respondWithCatchError(onRejected, this.reason, resolve, reject); } if (this.status === STATUS_PENDING) { this.onResolvedCallbacks.push(() => { respondWithCatchError(onFulfilled, this.value, resolve, reject); }); this.onRejectedCallbacks.push(() => { respondWithCatchError(onRejected, this.reason, resolve, reject); }); } }); } catch(onRejected) { this.then(null, onRejected); } finally(onFinally) { this.then( () => { onFinally(); }, () => { onFinally(); } ); }}// 测试代码const promise = new IcePromise((resolve, reject) => { reject("----reject");});promise .then( (value) => { console.log("res1", value); }, (reason) => { console.log("err1", reason); } ) .finally(() => { console.log("finally"); });resolve/reject
resolve和reject是Promise的类办法，也能够通过调用then办法来实现
static resolve(value){ return new icePromise((resolve)=>resolve(value))}static reject(reason){ return new icePromise((resolve, reject)=>reject(reason))}残缺实现如下
const STATUS_PENDING = "pending";const STATUS_FULFILLED = "fulfilled";const STATUS_REJECTED = "rejected";const respondWithCatchError = (fn, value, resolve, reject) => { try { const result = fn(value); resolve(result); } catch (error) { reject(error); }};class IcePromise { constructor(executor) { this.status = STATUS_PENDING; this.onResolvedCallbacks = []; this.onRejectedCallbacks = []; this.value = undefined; this.reason = undefined; const resolve = (value) => { if (this.status === STATUS_PENDING) { queueMicrotask(() => { if (this.status !== STATUS_PENDING) return; this.status = STATUS_FULFILLED; this.value = value; this.onResolvedCallbacks.forEach((fn) => { fn(this.value); }); }); } }; const reject = (reason) => { if (this.status === STATUS_PENDING) { queueMicrotask(() => { if (this.status !== STATUS_PENDING) return; this.status = STATUS_REJECTED; this.reason = reason; this.onRejectedCallbacks.forEach((fn) => { fn(this.reason); }); }); } }; executor(resolve, reject); } then(onFulfilled, onRejected) { const defaultOnFulfilled = (value) => { return value; }; const defaultOnRejected = (reason) => { throw reason; }; onFulfilled = onFulfilled || defaultOnFulfilled; onRejected = onRejected || defaultOnRejected; return new Promise((resolve, reject) => { if (this.status === STATUS_FULFILLED && onFulfilled) { respondWithCatchError(onFulfilled, this.value, resolve, reject); } if (this.status === STATUS_REJECTED && onRejected) { respondWithCatchError(onRejected, this.reason, resolve, reject); } if (this.status === STATUS_PENDING) { this.onResolvedCallbacks.push(() => { respondWithCatchError(onFulfilled, this.value, resolve, reject); }); this.onRejectedCallbacks.push(() => { respondWithCatchError(onRejected, this.reason, resolve, reject); }); } }); } catch(onRejected) { this.then(null, onRejected); } finally(onFinally) { this.then( () => { onFinally(); }, () => { onFinally(); } ); } static resolve(value) { return new Promise((onResolve) => { onResolve(value); }); } static reject(reason) { return new Promise((onResolve, onRejected) => { onRejected(reason); }); }}// 测试代码const promise = Promise.reject(1);promise .then( (value) => { console.log("res1", value); }, (reason) => { console.log("err1", reason); } )执行后果如下
all/allSettled
all和allSettled办法都是promise的类办法
1、all办法
只有有一个promise执行reject的办法就会执行reject，当所有promise都返回resolve时，才执行resolve办法。
2、allSettled办法
当所有promise都执行实现时，才执行resolve办法，返回所有promise的状态和后果。
static all(promise){ return new icePromise((resolve, reject)=>{ const values = [] promises.forEach(promise => { promise.then(res => { values.push(res) if (values.length === promises.length) { resolve(values) } }, err => { reject(err) }) }) }) })}static allSettled(promise){ return new icePromise((resolve, reject)=>{ const values = [] promise.then(res=>{ values.push({ status: '', value: '' }) if(values.length === promise.length){ resolve(values) } }, err=>{ values.push({ status: '', value: '' }) if(values.length === promise.length){ resolve(values) } }) })}残缺实现如下
const STATUS_PENDING = "pending";const STATUS_FULFILLED = "fulfilled";const STATUS_REJECTED = "rejected";const respondWithCatchError = (fn, value, resolve, reject) => { try { const result = fn(value); resolve(result); } catch (error) { reject(error); }};class IcePromise { constructor(executor) { this.status = STATUS_PENDING; this.onResolvedCallbacks = []; this.onRejectedCallbacks = []; this.value = undefined; this.reason = undefined; const resolve = (value) => { if (this.status === STATUS_PENDING) { queueMicrotask(() => { if (this.status !== STATUS_PENDING) return; this.status = STATUS_FULFILLED; this.value = value; this.onResolvedCallbacks.forEach((fn) => { fn(this.value); }); }); } }; const reject = (reason) => { if (this.status === STATUS_PENDING) { queueMicrotask(() => { if (this.status !== STATUS_PENDING) return; this.status = STATUS_REJECTED; this.reason = reason; this.onRejectedCallbacks.forEach((fn) => { fn(this.reason); }); }); } }; executor(resolve, reject); } then(onFulfilled, onRejected) { const defaultOnFulfilled = (value) => { return value; }; const defaultOnRejected = (reason) => { throw reason; }; onFulfilled = onFulfilled || defaultOnFulfilled; onRejected = onRejected || defaultOnRejected; return new Promise((resolve, reject) => { if (this.status === STATUS_FULFILLED && onFulfilled) { respondWithCatchError(onFulfilled, this.value, resolve, reject); } if (this.status === STATUS_REJECTED && onRejected) { respondWithCatchError(onRejected, this.reason, resolve, reject); } if (this.status === STATUS_PENDING) { this.onResolvedCallbacks.push(() => { respondWithCatchError(onFulfilled, this.value, resolve, reject); }); this.onRejectedCallbacks.push(() => { respondWithCatchError(onRejected, this.reason, resolve, reject); }); } }); } catch(onRejected) { this.then(null, onRejected); } finally(onFinally) { this.then( () => { onFinally(); }, () => { onFinally(); } ); } static resolve(value) { return new Promise((onResolve) => { onResolve(value); }); } static reject(reason) { return new Promise((onResolve, onRejected) => { onRejected(reason); }); } static all(promises) { return new Promise((resolve, reject) => { const result = []; promises.forEach((promise) => { promise.then( (value) => { result.push(value); if (result.length === promises.length) { resolve(result); } }, (reason) => { reject(reason); } ); }); }); } static allSettled(promises) { return new Promise((resolve, reject) => { const result = []; promises.forEach((promise) => { promise.then( (value) => { result.push({ status: STATUS_FULFILLED, value, }); if (result.length === promises.length) { resolve(result); } }, (reason) => { result.push({ status: STATUS_REJECTED, reason, }); if (result.length === promises.length) { resolve(result); } } ); }); }); }}// 测试代码const promise1 = IcePromise.resolve(1);const promise2 = new IcePromise((resolve, reject) => { setTimeout(() => { reject(2); });});const promise3 = IcePromise.resolve(3);IcePromise.all([promise1, promise2, promise3]).then( (value) => { console.log("res1", value); }, (reason) => { console.log("err1", reason); });IcePromise.allSettled([promise1, promise2, promise3]).then( (value) => { console.log("res2", value); }, (reason) => { console.log("err2", reason); });执行后果如下
race/any
race和any都是promise的类办法。
1、race办法
只有有一个promise执行实现，就会返回它所执行的后果
2、any办法
① 有fulfilled状态，会等到这个fullfilled执行实现，执行resolve，后果为value
② 如果所有的Promise都是reject的，那么也会等到所有的Promise都变成rejected状态后报一个AggregateError的谬误。
static race(promises){ return new icePromise((resolve, reject)=>{ promises.forEach(promise=>{ promise.then(resolve, reject) }) })}static any(promises){ const reasons = [] return new icePromise((resolve, reject)=>{ promises.forEach(promise=>{ promise.then(resolve, err=>{ reasons.push(err) if(reasons.length === promises.length){ reject(new AggregateError(reasons)) } }) }) })}整体实现如下
const STATUS_PENDING = "pending";const STATUS_FULFILLED = "fulfilled";const STATUS_REJECTED = "rejected";const respondWithCatchError = (fn, value, resolve, reject) => { try { const result = fn(value); resolve(result); } catch (error) { reject(error); }};class IcePromise { constructor(executor) { this.status = STATUS_PENDING; this.onResolvedCallbacks = []; this.onRejectedCallbacks = []; this.value = undefined; this.reason = undefined; const resolve = (value) => { if (this.status === STATUS_PENDING) { queueMicrotask(() => { if (this.status !== STATUS_PENDING) return; this.status = STATUS_FULFILLED; this.value = value; this.onResolvedCallbacks.forEach((fn) => { fn(this.value); }); }); } }; const reject = (reason) => { if (this.status === STATUS_PENDING) { queueMicrotask(() => { if (this.status !== STATUS_PENDING) return; this.status = STATUS_REJECTED; this.reason = reason; this.onRejectedCallbacks.forEach((fn) => { fn(this.reason); }); }); } }; executor(resolve, reject); } then(onFulfilled, onRejected) { const defaultOnFulfilled = (value) => { return value; }; const defaultOnRejected = (reason) => { throw reason; }; onFulfilled = onFulfilled || defaultOnFulfilled; onRejected = onRejected || defaultOnRejected; return new Promise((resolve, reject) => { if (this.status === STATUS_FULFILLED && onFulfilled) { respondWithCatchError(onFulfilled, this.value, resolve, reject); } if (this.status === STATUS_REJECTED && onRejected) { respondWithCatchError(onRejected, this.reason, resolve, reject); } if (this.status === STATUS_PENDING) { this.onResolvedCallbacks.push(() => { respondWithCatchError(onFulfilled, this.value, resolve, reject); }); this.onRejectedCallbacks.push(() => { respondWithCatchError(onRejected, this.reason, resolve, reject); }); } }); } catch(onRejected) { this.then(null, onRejected); } finally(onFinally) { this.then( () => { onFinally(); }, () => { onFinally(); } ); } static resolve(value) { return new Promise((onResolve) => { onResolve(value); }); } static reject(reason) { return new Promise((onResolve, onRejected) => { onRejected(reason); }); } static all(promises) { return new Promise((resolve, reject) => { const result = []; promises.forEach((promise) => { promise.then( (value) => { result.push(value); if (result.length === promises.length) { resolve(result); } }, (reason) => { reject(reason); } ); }); }); } static allSettled(promises) { return new Promise((resolve, reject) => { const result = []; promises.forEach((promise) => { promise.then( (value) => { result.push({ status: STATUS_FULFILLED, value, }); if (result.length === promises.length) { resolve(result); } }, (reason) => { result.push({ status: STATUS_REJECTED, reason, }); if (result.length === promises.length) { resolve(result); } } ); }); }); } static race(promises) { return new Promise((resolve, reject) => { promises.forEach((promise) => { promise.then(resolve, reject); }); }); } static any(promises) { return new Promise((resolve, reject) => { const reasons = []; promises.forEach((promise) => { promise.then(resolve, (reason) => { reasons.push(reason); if (reasons.length === promises.length) { reject(new AggregateError(reasons)); } }); }); }); }}// 测试代码const promise1 = new IcePromise((resolve, reject) => { setTimeout(() => { reject(1); });});const promise2 = IcePromise.reject(2);const promise3 = IcePromise.reject(3);IcePromise.race([promise1, promise2, promise3]).then( (value) => { console.log("res1", value); }, (reason) => { console.log("err1", reason); });IcePromise.any([promise1, promise2, promise3]).then( (value) => { console.log("res1", value); }, (reason) => { console.log("err1", reason); });以上就是自定义promise的所有代码啦，对于js高级，还有很多须要开发者把握的中央，能够看看我写的其余博文，继续更新中~