Demonstrating race conditions using globals in an express app.

broken_app.js

var express = require('express'),
    app = express(),
    userLoggedIn = false; // global shared between requests (just to show it not working, could be cookie based)

app.all('*', function(req, res, next) {

    var id = Date.now();
    userLoggedIn = Math.random() > 0.5 ? true : false; // imagine that this is based on some API call

    console.log('Rx request id %s with userLoggedIn as %s', id, userLoggedIn);

    var timer = Math.random() * 2500; // random response time

    setTimeout(function() {
        console.log('sending response id %s with userLoggedIn as %s', id, userLoggedIn);
        var someResponse = userLoggedIn ? 'Hello User' : 'Not Logged In';
        res.send(someResponse);
    }, timer);

});

app.listen(8000)