how to use router in nodejs code example

Example: route parameter in node

var express = require('express');
var fs  = require('fs');
var app= express();
 app.get('/index/profile/:id',function(req,res){
    //  res.send('profile with id' + req.params.id)

    
    
 });
app.listen(3000,'127.0.0.1');
console.log('lsitng');