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router.use() Method in Express.js
The router.use() method has an optional mount path which is set to "/" by default. This method uses the specified middleware functions for this optional mountpath. The method is similar to app.use().
Syntax
router.use( [path], [function, ...] callback )
Example 1
Create a file with the name "routerUse.js" and copy the following code snippet. After creating the file, use the command "node routerUse.js" to run this code as shown in the example below:
// router.use() Method Demo Example
// Importing the express module
const express = require('express');
// Initializing the express and port number
var app = express();
// Initializing the router from express
var router = express.Router();
var PORT = 3000;
// If the endpoint not found default is called
router.use(function (req, res, next) {
console.log("Middleware Called");
next();
})
// This method is always invoked
router.use(function (req, res, next) {
console.log("Welcome to Tutorials Point");
res.send("Welcome to Tutorials Point");
})
app.use('/api', router);
app.listen(PORT, function(err){
if (err) console.log(err);
console.log("Server listening on PORT", PORT);
});Hit the following Endpoint with a GET request − http://localhost:3000/api
Output
C:\home
ode>> node routerUse.js Server listening on PORT 3000 Middleware Called Welcome to Tutorials Point
Example 2
Let's take a look at one more example.
// router.use() Method Demo Example
// Importing the express module
const express = require('express');
// Initializing the express and port number
var app = express();
// Initializing the router from express
var router = express.Router();
var PORT = 3000;
// All requests will hit this middleware
router.use(function (req, res, next) {
console.log('Method: %s URL: %s Path: %s', req.method, req.url, req.path)
next()
})
// this will only be invoked if the path starts with /v1 from the mount point
router.use('/v1', function (req, res, next) {
console.log("/v1 is called")
next()
})
// always invoked
router.use(function (req, res, next) {
res.send('Welcome to Tutorials Point')
})
app.use('/api', router)
app.listen(PORT, function(err){
if (err) console.log(err);
console.log("Server listening on PORT", PORT);
});Hit the following Endpoint one by one with a GET request −
- http://localhost:3000/api
- http://localhost:3000/api/v1
Output
C:\home
ode>> node routerUse.js Server listening on PORT 3000 Method: GET URL: / Path: / Method: GET URL: /v1 Path: /v1 /v1 is called
Updated on: 29-Jan-2022
1K+ Views
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