expressjsWhat is Express.js and how is it used for software development?

Express.js is a web application framework for Node.js, released as free and open-source software under the MIT License. It is designed for building web applications and APIs. It has been called the de facto standard server framework for Node.js.

Express.js simplifies the development of web applications and APIs by providing a set of features that allow developers to quickly create robust and secure web applications. For example, Express.js provides a routing system that allows developers to easily define routes and associated HTTP methods (GET, POST, PUT, etc.). Additionally, Express.js provides middleware support, allowing developers to easily add functionality to their applications.

Example code

const express = require('express');
const app = express();

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

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

Output example

Example app listening on port 3000!

Code explanation

1. const express = require('express') - this loads the Express.js module, which provides the necessary functions for creating a web application.
2. const app = express() - this creates an instance of an Express.js application.
3. app.get('/', (req, res) => {...}) - this defines a route that will be used to handle a GET request to the root path of the application.
4. res.send('Hello World!') - this is the response that will be sent to the client when the route is accessed.
5. app.listen(3000, () => {...}) - this starts the application and tells it to listen for requests on port 3000.

Helpful links

• Express.js Documentation
• Express.js Tutorial

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