Custom middleware in Express

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);

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