Hello World 示例

¥Hello world example

下面嵌入的本质上是你可以创建的最简单的 Express 应用。它是一个单文件应用 - 不是你使用 Express 生成器 所得到的,它为包含大量 JavaScript 文件、Jade 模板和用于各种目的的子目录的完整应用创建了脚手架。

¥Embedded below is essentially the simplest Express app you can create. It is a single file app — not what you’d get if you use the Express generator, which creates the scaffolding for a full app with numerous JavaScript files, Jade templates, and sub-directories for various purposes.

const express = require('express')
const app = express()
const port = 3000

app.get('/', (req, res) => {
  res.send('Hello World!')

app.listen(port, () => {
  console.log(`Example app listening on port ${port}`)

此应用启动一个服务器并在端口 3000 上监听连接。应用以 “Hello World!” 响应对根 URL (/) 或路由的请求。对于所有其他路径,它将响应 404 Not Found。

¥This app starts a server and listens on port 3000 for connections. The app responds with “Hello World!” for requests to the root URL (/) or route. For every other path, it will respond with a 404 Not Found.

上面的例子实际上是一个工作服务器:继续并单击显示的 URL。你会收到响应,页面上会显示实时日志,并且你所做的任何更改都会实时反映。这由 RunKit 提供支持,它提供了一个交互式 JavaScript 在线运行,连接到在你的 Web 浏览器中运行的完整 Node 环境。以下是在本地计算机上运行相同应用的说明。

¥The example above is actually a working server: Go ahead and click on the URL shown. You’ll get a response, with real-time logs on the page, and any changes you make will be reflected in real time. This is powered by RunKit, which provides an interactive JavaScript playground connected to a complete Node environment that runs in your web browser. Below are instructions for running the same app on your local machine.

RunKit 是一个第三方服务,不隶属于 Express 项目。

¥RunKit is a third-party service not affiliated with the Express project.


¥Running Locally

首先创建一个名为 myapp 的目录,切换到它并运行 npm init。然后按照 安装指南 安装 express 作为依赖。

¥First create a directory named myapp, change to it and run npm init. Then install express as a dependency, as per the installation guide.

myapp 目录中,创建一个名为 app.js 的文件并复制上面示例中的代码。

¥In the myapp directory, create a file named app.js and copy in the code from the example above.

req(请求)和 res(响应)与 Node 提供的对象完全相同,因此你可以调用 req.pipe()req.on('data', callback) 以及无需 Express 参与的任何其他操作。

¥The req (request) and res (response) are the exact same objects that Node provides, so you can invoke req.pipe(), req.on('data', callback), and anything else you would do without Express involved.


¥Run the app with the following command:

$ node app.js

然后,在浏览器中加载 http://localhost:3000/ 以查看输出。

¥Then, load http://localhost:3000/ in a browser to see the output.