express安装

文档：http://expressjs.com/

Assuming you’ve already installed Node.js, create a directory to hold your application, and make that your working directory.

mkdir myapp
cd myapp

Use the npm init command to create a package.json file for your application. For more information on how package.json works, see Specifics of npm’s package.json handling.

npm init

This command prompts you for a number of things, such as the name and version of your application. For now, you can simply hit RETURN to accept the defaults for most of them, with the following exception:

entry point: (index.js)

Enter app.js, or whatever you want the name of the main file to be. If you want it to be index.js, hit RETURN to accept the suggested default file name.

Now install Express in the myapp directory and save it in the dependencies list. For example:

npm install express --save

To install Express temporarily and not add it to the dependencies list, omit the --save option:

npm install express

---

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

In the myapp directory, create a file named app.js and add the following code

var express = require('express')
var app = express()

app.get('/', function (req, res) {
  res.send('Hello World!')
})

app.listen(3000, function () {
  console.log('Example app listening on port 3000!')
})

Run the app with the following command:

node app.js