Express.js

  • Last Updated : 16 Jan, 2022

Express.js is a small framework that works on top of Node.js web server functionality to simplify its APIs and add helpful new features. It makes it easier to organize your application’s functionality with middleware and routing. It adds helpful utilities to Node.js HTTP objects and facilitates the rendering of dynamic HTTP objects.

Express.js Tutorial

Why Express ?

  • Develops Node.js web applications quickly and easily.
  • It’s simple to set up and personalise.
  • Allows you to define application routes using HTTP methods and URLs.
  • Includes a number of middleware modules that can be used to execute additional requests and responses activities.
  • Simple to interface with a variety of template engines, including Jade, Vash, and EJS.
  • Allows you to specify a middleware for handling errors.

Installing Express:

We can install it with npm. Make sure that you have Node.js and npm installed.

Step 1: Creating a directory for our project and make that our working directory.

$ mkdir gfg
$ cd gfg 

Step 2: Using npm init command to create a package.json file for our project.

$ npm init

This command describes all the dependencies of our project. The file will be updated when adding further Installing Express

Step 3: Now in your gfg(name of your folder) folder type the following command line:

$ npm install express --save

Now let’s understand the working of express.js through an example.

Project Structure: It will look like the following.

Project Structure

Example: Write the following code in app.js.

app.js

var express = require('express');
var app = express();
app.get('/', function (req, res) {
res.send("Welocme to GeeksforGeeks!");
});
app.listen(5000);

Step to run the application: Start the app by typing following command.

node app.js

Output:

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