Description and usage of promise in javascript

This article mainly explains "the explanation and usage of promise in javascript". Interested friends may wish to have a look at it. The method introduced in this paper is simple, fast and practical. Let's let the editor take you to learn "the explanation and usage of promise in javascript".

Description

1. If a task depends on multiple asynchronous tasks, you can use Promise.all.

2. If a task depends on any one of multiple asynchronous tasks, then Promise.race doesn't matter.

Example

Var defer = function () {var pending = [], value; return {resolve: function (_ value) {value = _ value; for (var I = 0, ii = pending.length; I < ii; iTunes +) {var callback = pending [I]; callback (value);} pending = undefined }, then: function (callback) {if (pending) {pending.push (callback);} else {callback (value);}. At this point, I believe you have a deeper understanding of "the description and use of promise in javascript". You might as well do it in practice! Here is the website, more related content can enter the relevant channels to inquire, follow us, continue to learn!