如何使用 js 实现一个 Promise.all 方法

如何使用 js 实现一个 Promise.all 方法

Promise.all

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise/all

"use strict";

/**
 *
 * @author xgqfrms
 * @license MIT
 * @copyright xgqfrms
 * @created 2020-08-0
 * @modified
 *
 * @description
 * @difficulty Easy Medium Hard
 * @complexity O(n)
 * @augments
 * @example
 * @link https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise/all
 * @solutions
 *
 */

const log = console.log;

const promise1 = Promise.resolve(3);
const promise2 = 42;
const promise3 = new Promise((resolve, reject) => {
  setTimeout(resolve, 0, 'foo');
});
const promise4 = new Promise((resolve, reject) => {
  reject(`promise error`);
});

const promisesOK = [promise1, promise2, promise3];
const promisesError = [promise1, promise2, promise3, promise4];

const OK = Promise.all(promisesOK).then((values) => {
  log(`promisesOK values =`, values);
});


const Error = Promise.all(promisesError).then((values) => {
  log(`promisesError values =`, values);
}).catch(err => {
  log(`error =`, err)
});

setTimeout(() => {
  log(`\nOK =`, OK)
  log(`Error =`, Error)
}, 5);

/*

$ node promise.all.js

error = promise error
promisesOK values = [ 3, 42, 'foo' ]

OK = Promise { undefined }
Error = Promise { undefined }

*/

refs

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Using_promises

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise

Promise

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