how to use router in node js code example

Example 1: express router file

var express = require('express');
var router = express.Router();

// middleware that is specific to this router
router.use(function timeLog (req, res, next) {
  console.log('Time: ', Date.now());
  next();
});
// define the home page route
router.get('/', function (req, res) {
  res.send('Birds home page');
});
// define the about route
router.get('/about', function (req, res) {
  res.send('About birds');
});

module.exports = router;

Example 2: express route parameters

Route path: /users/:userId/books/:bookId
Request URL: http://localhost:3000/users/34/books/8989
req.params: { "userId": "34", "bookId": "8989" }

Example 3: express() vs express.router()

var express = require('express'),
    dogs    = require('./routes/dogs'),
    cats    = require('./routes/cats'),
    birds   = require('./routes/birds');

var app = express();

app.use('/dogs',  dogs);
app.use('/cats',  cats);
app.use('/birds', birds);

app.listen(3000);

Example 4: express route parameters

var express = require('express');
var http = require('http');
var app = express();

Example 5: express() vs express.router()

var express = require('express');

var router = express.Router();

router.get('/', function(req, res) {
    res.send('GET handler for /dogs route.');
});

router.post('/', function(req, res) {
    res.send('POST handler for /dogs route.');
});

module.exports = router;