In Express, you can define middlewares that can be used for checking requests or setting some headers in response.
app.use(function(req, res, next){ }); // signatureExample
The following code adds user to the request object and pass the control to the next matching route.
var express = require('express');
var app = express();
//each request will pass through it
app.use(function(req, res, next){
req.user = 'testuser';
next(); // it will pass the control to next matching route
});
app.get('/', function(req, res){
var user = req.user;
console.log(user); // testuser
return res.send(user);
});
app.listen(3000);