In nodejs, await is used to pause execution in a non-blocking manner, waiting for a promise's asynchronous request, and waiting for the asynchronous method to complete execution; await can be used in async functions to wait for the return of an async function Value; promise returns an unsuccessful rejection, and the rejection value will be thrown and can be captured by "try/catch".
The operating environment of this article: Windows 10 system, nodejs version 12.19.0, Dell G3 computer.
How to use await in nodejs
Async/await usage was introduced in Node.js 7 night, but it is only possible to officially activate the async/await function in Node.js 8 and Javascript V8.
What is async/await? How to implement asynchronous operations using Promise in the past. The following case shows how to use Promise and Fetch API to capture data:
function getTrace () { return fetch('https://www.jdon.com', { method: 'get' }) } getTrace() .then() .catch()
Using async/await, you can pause execution in a non-blocking manner and wait for the result to return. If the promise returns an unsuccessful rejection, the rejection value will be thrown and can be captured by try/catch. The above case can be written as follows using async/await:
function async getTrace () { let pageContent try { pageContent = await fetch('https://www.jdon.com', { method: 'get' }) } catch (ex) { console.error(ex) } return pageContent } getTrace() .then()
Let’s look at the case of using async/await in Node.js, using setimeout to delay the execution of a function, and using async/await encapsulation:
// app.js const timeout = function (delay) { return new Promise((resolve, reject) => { setTimeout(() => { resolve() }, delay) }) } async function timer () { console.log('timer started') await Promise.resolve(timeout(100)); console.log('timer finished') } timer()
Create this app.js file and run:
node app.js
If it cannot run, it may be that nodejs is a nightly version and does not officially support async/await. The command line should be:
node --harmony-async-await app.js
Recommended learning: "nodejs video tutorial"
The above is the detailed content of How to use await in nodejs. For more information, please follow other related articles on the PHP Chinese website!

Vercel是什么?本篇文章带大家了解一下Vercel,并介绍一下在Vercel中部署 Node 服务的方法,希望对大家有所帮助!

gm是基于node.js的图片处理插件,它封装了图片处理工具GraphicsMagick(GM)和ImageMagick(IM),可使用spawn的方式调用。gm插件不是node默认安装的,需执行“npm install gm -S”进行安装才可使用。

大家都知道 Node.js 是单线程的,却不知它也提供了多进(线)程模块来加速处理一些特殊任务,本文便带领大家了解下 Node.js 的多进(线)程,希望对大家有所帮助!

今天跟大家介绍一个最新开源的 javaScript 运行时:Bun.js。比 Node.js 快三倍,新 JavaScript 运行时 Bun 火了!

node怎么爬取数据?下面本篇文章给大家分享一个node爬虫实例,聊聊利用node抓取小说章节的方法,希望对大家有所帮助!

在nodejs中,lts是长期支持的意思,是“Long Time Support”的缩写;Node有奇数版本和偶数版本两条发布流程线,当一个奇数版本发布后,最近的一个偶数版本会立即进入LTS维护计划,一直持续18个月,在之后会有12个月的延长维护期,lts期间可以支持“bug fix”变更。


Hot AI Tools

Undresser.AI Undress
AI-powered app for creating realistic nude photos

AI Clothes Remover
Online AI tool for removing clothes from photos.

Undress AI Tool
Undress images for free

Clothoff.io
AI clothes remover

AI Hentai Generator
Generate AI Hentai for free.

Hot Article

Hot Tools

ZendStudio 13.5.1 Mac
Powerful PHP integrated development environment

SAP NetWeaver Server Adapter for Eclipse
Integrate Eclipse with SAP NetWeaver application server.

EditPlus Chinese cracked version
Small size, syntax highlighting, does not support code prompt function

DVWA
Damn Vulnerable Web App (DVWA) is a PHP/MySQL web application that is very vulnerable. Its main goals are to be an aid for security professionals to test their skills and tools in a legal environment, to help web developers better understand the process of securing web applications, and to help teachers/students teach/learn in a classroom environment Web application security. The goal of DVWA is to practice some of the most common web vulnerabilities through a simple and straightforward interface, with varying degrees of difficulty. Please note that this software

Atom editor mac version download
The most popular open source editor
