Node.js Web Apps With Express Custom middleware in Express


Example

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){ });    // signature

Example

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);