What is Express Js

• Express.js is a web application framework for Node.js, designed to simplify the process of building robust and scalable web applications and APIs. It provides a set of features and tools that make it easier to handle tasks such as routing, middleware management, and request/response handling.

Here are some key points about Express.js:

• Web Application Framework: Express.js is a minimal and flexible Node.js web application framework that provides a set of features for building web and mobile applications.

• Routing: It allows you to define routes to handle different HTTP methods (GET, POST, etc.) and URLs. This helps in organizing your application and handling specific requests with corresponding functions.

    const express = require('express');

    const app = express();

    app.get('/', (req, res) => {

        res.send('Hello, Express!');

    });

    app.listen(3000, () => {

        console.log('Server is running on port 3000');

    });

• Middleware: Express uses middleware functions to execute code during the request-response cycle. Middleware functions have access to the request, response, and the next middleware function in the cycle.

    const express = require('express');

    const app = express();

    // Middleware function

    app.use((req, res, next) => {

        console.log('Middleware executed');

        next(); // Move to the next middleware or route handler

    });

    app.get('/', (req, res) => {

        res.send('Hello, Express!');

    });

    app.listen(3000, () => {

        console.log('Server is running on port 3000');

    });

• Template Engines: Express supports various template engines (like EJS, Pug) to dynamically generate HTML on the server side.

• Static Files: It allows you to serve static files (like images, stylesheets) easily using the `express.static` middleware.

    // Serve static files from the 'public' directory

    app.use(express.static('public'));

• Express.js is widely used in the Node.js community for building both small and large-scale web applications due to its simplicity and flexibility.