The Request Object (req)
The req object represents the HTTP request and has properties for the request query string, parameters, body, HTTP headers, and so on.
Core Properties
| Property | Description | Example |
|---|
req.params | URL segments (:id) | /user/:id |
req.query | Query strings (?q=) | /search?q=node |
req.body | Parsed body data | POST payloads |
req.headers | HTTP Headers | Authorization, Content-Type |
req.ip | Remote IP segment | 127.0.0.1 |
req.path | Request URL path | /users/list |
Accessing URL Parameters
// Route: /api/users/:id
app.get('/api/users/:id', (req, res) => {
console.log(req.params.id);
res.send('User ID is ' + req.params.id);
});
Checking Headers
You can check if a request contains specific authorization or metadata.
app.get('/admin', (req, res) => {
const adminKey = req.get('x-admin-key'); // Get header
if (adminKey === 'SECRET') {
res.send('Welcome Admin');
} else {
res.status(403).send('Forbidden');
}
});
Important: req.body will be undefined unless you use a body-parsing middleware like express.json().
