Comprehensive Guide

introduction:

Express.js is a popular web application framework that simplifies building reliable and scalable web applications for Node.js. As a developer working with Express.js, it is important to familiarize yourself with the various commands and utilities it offers to increase your productivity. In this article, we'll explore a set of Express.js commands that allow you to efficiently manage routing, middleware, and application configuration.

Setup and Installation:

• Install Express.js: npm install Express
• Create an Express application: const Express = require('Express'); const program = express();
• Start server: app.listen(port, () => { console.log('Server started on port ' + port); });

Route:

• Set main path: app.get('/', (req, res) => { res.send('Hello, World!'); });
• Route parameters: app.get('/users/:id', (req, res) => { const userId = req.params.id; /.../ });
• Handle Controllers: app.get('/users', getUsers);

Middleware:

• Run the middleware: app.use(middleware);
• Body analysis: app.use(Express.json()); and app.use (Express.urlencoded ({extended: true}));
• Login request: app.use ((req, res, next) => { console.log('Request:',req.method,req.url); next(); });

Error handling:

• Handle errors with middleware: app.use ((error, req, res, next) => {/.../});
• private Error handler: app.use((error, req, res, next) => { /.../ res.status(500).json({error: 'Something went wrong.'});}) ;

Static files:

• Serve a static file: app.use(Express.static('public'));
• Define static file directory: app.use('/assets', Express.static('public/assets'));

Template Engine:
Set the template engine (eg EJS): app.set('view engine', 'ejs');
Render: res.render( 'index', { title: 'Home' });

Middleware Library:

• Express.js provides a variety of middleware libraries that can be easily integrated into your application:
• Body-manager: Build npm body-manager
• Cookie-parser: Install npm cookie-parser
• Cask: Install npm shell
• Morgan: npm build morgan

additional services:

• HTTP methods other than GET: app.post(), app.put(), app.delete(), etc.
• Route group: app.use('/api', router);
• Validate paramol parameters: Use libraries like express-validator or custom validation functions.
• Redirect: res.redirect('/new-location'); The results: Express.js Command Node.js. form the core of building a powerful web application with This comprehensive guide provides an overview of the essential commands for building an Express.js application, routing, middleware, error handling, static file portions, working with the template engine, and using additional utilities. By mastering these commands, you'll be equipped to build responsive and scalable web applications using Express.js.