Express Request

In Express.js, handling HTTP requests is a fundamental aspect of building web applications. Express provides a simple and intuitive way to handle incoming requests.

Here's an overview of handling requests in Express:

Request Handling:

Request Object (req):

The req object represents the HTTP request and contains information about the request, such as parameters, query strings, headers, and more.

Accessing query parameters:

app.get('/user', (req, res) => {
  const userId = req.query.id;
  res.send(`User ID: ${userId}`);
});

Note: If the URL is /user?id=778899, req.query.id will be '778899'.

Accessing route parameters:

app.get('/user/:id', (req, res) => {
  const userId = req.params.id;
  res.send(`User ID: ${userId}`);
});

Note: If the URL is /user/778899, req.params.id will be '778899'.

Accessing request headers:

app.get('/headers', (req, res) => {
  const userAgent = req.get('User-Agent');
  const accept = req.get('accept');
  console.log(`User-Agent: ${userAgent}, accept: ${accept} `)
  res.send(`User-Agent: ${userAgent}, accept: ${accept} `);
});

Handling a GET request:

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

const PORT = process.env.PORT || 3000;

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


app.listen(PORT, () => {
  console.log(`Server is running on http://localhost:${PORT}`);
});

"app.get" is used to define a route for handling HTTP GET requests on the root URL ("/"). The callback function takes req (request) and res (response) as parameters.

Handling a POST request:

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

const PORT = process.env.PORT || 3000;

app.post('/add-user', (req, res) => {
  const {body} = req;
  console.log("Print Body", body);
  res.send('Add User Request Received');
});


app.listen(PORT, () => {
  console.log(`Server is running on http://localhost:${PORT}`);
});

"app.post" is used to define a route for handling HTTP POST requests on the URL ("/add-user"). The callback function takes req (request) and res (response) as parameters.

Handling a PUT request:

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

const PORT = process.env.PORT || 3000;

app.put('/update-user', (req, res) => {
  const {body} = req;
  console.log("Print Body", body);
  res.send('Update User Request Received');
});


app.listen(PORT, () => {
  console.log(`Server is running on http://localhost:${PORT}`);
});

"app.put" is used to define a route for handling HTTP PUT requests on the URL ("/update-user"). The callback function takes req (request) and res (response) as parameters.

Handling a DELETE request:

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

const PORT = process.env.PORT || 3000;

app.delete('/delete-user', (req, res) => {
  const {userId} = req.query;
  console.log("Print UserId", userId);
  res.send('delete User Request Received');
});


app.listen(PORT, () => {
  console.log(`Server is running on http://localhost:${PORT}`);
});

"app.delete" is used to define a route for handling HTTP DELETE requests on the URL ("/delete-user"). The callback function takes req (request) and res (response) as parameters.

Start Server Command:

 // navigate to folder location where server.js exist

node server.js

<-- Express Installation

Response -->