Category: 01. Express Js

For real-time communication, you can use WebSockets with the ws library or socket.io. a. Install Socket.IO b. Set Up Socket.IO In app.js:

Handle file uploads using middleware like multer. a. Install Multer b. Configure Multer In app.js: Here, dest specifies the directory where files will be stored, and upload.single(‘file’) handles single file uploads.

Securing your Express application is crucial to prevent common vulnerabilities. Here are some best practices and tools to help with that. a. Helmet Helmet helps secure your Express apps by setting various HTTP headers. In your app.js: b. Rate Limiting Limit the number of requests from a single IP to prevent abuse. In your app.js:…

Testing is crucial for ensuring your application works correctly. a. Install Testing Libraries For unit and integration tests, you might use libraries like Mocha and Chai. b. Write Tests Create a test directory and a test file, e.g., test/app.test.js: c. Run Tests Add a test script in package.json: Run your tests:

Use environment variables to manage configuration, like database connection strings, API keys, etc. a. Install dotenv b. Create a .env File c. Use Environment Variables In app.js:

Express can manage sessions using middleware like express-session. a. Install express-session b. Configure Sessions c. Use Sessions

Query parameters can be accessed through req.query. For example: You can access http://localhost:3000/search?q=express to see the results.

Express can render dynamic HTML pages using template engines like EJS, Pug, or Handlebars. a. Installing a Template Engine For EJS, install it with npm: Set up EJS in app.js: Create a views directory and add an index.ejs file: Render the template in your route:

Express supports modular routing, which can help organize your code better. a. Creating Router Modules You can create a separate file for your routes. For example, create a file named userRoutes.js: In your app.js:

Middleware functions are a core feature of Express.js. They can be used to handle requests, modify request and response objects, end requests, and call the next middleware function in the stack. a. Creating Custom Middleware Here’s an example of custom middleware that logs the request method and URL: b. Error Handling Middleware In Express, error…