Mastering Express JS Concepts

What is Express JS?

• A programming language for web development.

• A front-end framework for building user interfaces.

• Express JS is a web application framework for Node.js.

• A database management system.

How do you install Express JS in a Node.js project?

• Use 'yarn add express' instead of npm.

• Run 'npm start express' in your project directory.

• Run 'npm install express' in your project directory.

• Install Express by downloading it from the official website.

What is middleware in Express JS?

• Middleware is a tool for managing server hardware in Express JS.

• Middleware is a type of database in Express JS.

• Middleware in Express JS is a function that processes requests and responses.

• Middleware is a front-end framework for building user interfaces.

How can you define a route in Express JS?

• app.get('/path', (req) => { return 'Hello World!'; });

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

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

• app.route('/path', (req, res) => { res.send('Goodbye World!'); });

What is the purpose of the `app.listen()` method?

• To connect to a database server.

• To start a server and listen for incoming requests on a specified port.

• To define middleware functions for the app.

• To create a new application instance.

How do you handle GET requests in Express JS?

• Use app.post('/route', (req, res) => { res.send('response'); });

• app.get('/route', function(req) { return 'response'; });

• app.get('/route', (req, res) => { res.json('response'); });

• Use app.get('/route', (req, res) => { res.send('response'); });

What is the difference between `req.params` and `req.query`?

• `req.params` is for route parameters in the URL path, while `req.query` is for query string parameters.

• `req.params` and `req.query` are interchangeable and serve the same purpose.

• `req.params` is used for headers, while `req.query` is used for cookies.

• `req.params` is for query string parameters, while `req.query` is for route parameters in the URL path.

How can you serve static files using Express JS?

• Set up a separate server for static file hosting.

• Implement a middleware function to handle static files manually.

• Use 'app.get(directoryPath, handler)' to serve static files.

• Use 'app.use(express.static(directoryPath))' to serve static files.

What is the role of the `next` function in middleware?

• The `next` function allows middleware to pass control to the next middleware function.

• The `next` function is used to log requests only.

• The `next` function is a method for handling errors.

• The `next` function terminates the middleware process.

How do you handle errors in Express JS?

• Return a generic error message without details.

• Use error-handling middleware with four parameters (err, req, res, next) to handle errors in Express JS.

• Ignore errors and continue processing requests.

• Use console.log to display errors in the terminal.