Express req.params Property

The req.params property is an object that contains route parameters extracted from the URL. For example, if you define a route as /student/:id, you can access the value of id using req.params.id. If a route has no parameters, req.params is an empty object ({}).

Syntax:

req.params

Parameter: No parameters. 

Return Value: Returns an object containing the route parameters as key-value pairs.

Steps to Install the express module:

Step 1: You can install this package by using this command.

npm install express

Step 2: After installing the express module, you can check your express version in the command prompt using the command.

npm version express

Step 3: After that, you can just create a folder and add a file, for example, index.js. To run this file you need to run the following command.

node index.js

Project Structure:

Example 1: Below is the code of req.params Property implementation.

const express = require('express');
const app = express();
const PORT = 3000;
app.get('/:id', function (req, res) {
    console.log(req.params.id);
    res.send();
});
app.listen(PORT, function (err) {
    if (err) console.log(err);
    console.log("Server listening on PORT", PORT);
});

Steps to run the program:

Run the index.js file using the below command:

node index.js

Console Output:

Server listening on PORT 3000

Browser Output: Now open your browser and go to http://localhost:3000/123, now you can see the following output on your console:

Example 2: Below is the code of req.params Property implementation.

const express = require('express');
const app = express();
const PORT = 3000;
const student = express.Router();
app.use('/student', student);
student.get('/profile/:start/:end', function (req, res) {
    console.log("Starting Page: ", req.params.start);
    console.log("Ending Page: ", req.params.end);
    res.send();
})
app.listen(PORT, function (err) {
    if (err) console.log(err);
    console.log("Server listening on PORT", PORT);
});

Steps to run the program: Run the index.js file using the below command:

node index.js

Output: Send a GET request to http://localhost:3000/student/profile/12/17, now you can see the following output on your console:

Working of req.params

• The client sends a request containing route parameters in the URL.
• Express matches the URL with the defined route.
• The route parameters are extracted and stored in req.params.
• You can access individual values using their parameter names, such as req.params.id.

Common Use Cases of req.params

• Accessing user IDs from URLs.
• Retrieving product or order IDs.
• Loading blog posts using a slug.
• Creating RESTful APIs with dynamic routes.