ExpressJS - Setting up

• ExpressJS can be set up in a Node.js project using npm.
• First, initialize a new Node.js project using npm init.
• Then, install ExpressJS as a dependency using npm install express.
• Create a JavaScript file (e.g., app.js) and import Express.
• Define routes and middleware to handle requests and responses.

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1. Initialize a Node.js Project

Before setting up ExpressJS, ensure you have Node.js installed on your system. Then, navigate to your project directory and run the following command to initialize a new Node.js project:

npm init -y

This command will create a package.json file with default values.

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2. Install ExpressJS

Once the Node.js project is initialized, you can install ExpressJS as a dependency using npm. Run the following command:

npm install express

This command will install ExpressJS and add it to the dependencies list in your package.json file.

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3. Create an Express Application

After installing ExpressJS, you can create an Express application by creating a JavaScript file (e.g., app.js) and importing Express:

const express = require('express');
const app = express();

// Define routes and middleware here

app.listen(3000, () => {
  console.log('Server is running on port 3000');
});

In this example, an Express application is created, and it listens for incoming HTTP requests on port 3000.

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4. Define Routes and Middleware

With the Express application set up, you can define routes and middleware to handle incoming requests and generate responses. For example:

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

This code defines a route that responds with "Hello, World!" when the root URL is accessed.

Similarly, you can define more routes and middleware to handle various aspects of your application logic.

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5. Conclusion

With these steps, you have successfully set up an ExpressJS application and are ready to start building your web server or API.