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Node js tutorial step by step 15 More on Express Video Lecture | The Complete NodeJS Developer Course (in Hindi) - Back-End Programming

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FAQs on Node js tutorial step by step 15 More on Express Video Lecture - The Complete NodeJS Developer Course (in Hindi) - Back-End Programming

1. What is Express.js and why is it commonly used for back-end programming in Node.js?
Ans. Express.js is a popular web application framework for Node.js. It is commonly used for back-end programming in Node.js because it provides a simple and minimalistic approach to building web applications and APIs. Express.js offers various features such as routing, middleware support, and easy integration with other libraries, making it efficient and convenient for developers.
2. How can I install Express.js in my Node.js project?
Ans. To install Express.js in your Node.js project, you can use npm (Node Package Manager). Open the command prompt or terminal in your project directory and run the following command: ``` npm install express ``` This command will download and install the latest version of Express.js in your project, and it will be added as a dependency in your `package.json` file.
3. How can I create a basic Express.js server and handle HTTP requests?
Ans. To create a basic Express.js server, you need to require the Express module and create an instance of the Express application. Here's an example: ```javascript 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'); }); ``` In this example, the server is listening on port 3000, and when a GET request is made to the root URL ("/"), it responds with the message "Hello, Express!".
4. How can I handle URL parameters and query parameters in Express.js?
Ans. Express.js provides a convenient way to handle URL parameters and query parameters. URL parameters are defined in the route path using a colon followed by the parameter name. Query parameters are extracted from the request object's `query` property. Here's an example for both cases: ```javascript app.get('/users/:id', (req, res) => { const userId = req.params.id; // Handle the user ID }); app.get('/search', (req, res) => { const query = req.query.q; // Handle the search query }); ``` In the first example, the `:id` is a URL parameter, and in the second example, `q` is a query parameter.
5. How can I use middleware in Express.js?
Ans. Middleware functions in Express.js are functions that have access to the request and response objects, and can modify them or perform additional operations before passing them to the next middleware function. Middleware functions can be used for various purposes such as logging, authentication, error handling, etc. Here's an example of using middleware in Express.js: ```javascript app.use((req, res, next) => { console.log('Middleware function'); next(); }); app.get('/', (req, res) => { res.send('Hello, Express!'); }); ``` In this example, the middleware function is executed for every request, and it logs a message to the console before passing the request to the next middleware or route handler.
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