Node.js : How to do something on all HTTP requests in Express?

Express is based on the Connect middleware.

The routing capabilities of Express are provided by the router of your app and you are free to add your own middlewares to your application.

var app = express.createServer();

// Your own super cool function
var logger = function(req, res, next) {
    console.log("GOT REQUEST !");
    next(); // Passing the request to the next handler in the stack.
}

app.configure(function(){
    app.use(logger); // Here you add your logger to the stack.
    app.use(app.router); // The Express routes handler.
});

app.get("https://stackoverflow.com/", function(req, res){
    res.send('Hello World');
});

app.listen(3000);

It’s that simple.

(PS : If you just want some logging you might consider using the logger provided by Connect)