1 var express = require(‘express‘); 2  3 var app = express(); 4 var router = express.Router(); 5  6 app.get(‘/‘, function(req, res){ 7      console.log(‘test1‘); 8 }); 9 10 app.use(‘/‘, function(req, res){11      console.log(‘test2‘);12 });13 14 router.get(‘/‘, function(req, res){15      console.log(‘test3‘);16 });17 18 app.listen(4000);

1 app.use([path], [function...], function)2 Mount the middleware function(s) at the path. If path is not specified, it defaults to "/".3 4 Mounting a middleware at a path will cause the middleware function to be executed whenever the base of the requested path matches the path.