Express middleware before response is carried out to client

Well you can override the send function:

app.use(function (req, res) {    var send = res.send;    res.send = function (body) { // It might be a little tricky here, because send supports a variety of arguments, and you have to make sure you support all of them!        // Do something with the body...        send.call(this, body);    };});

If you want to support more than just calling send(like calling end method), then you have to override more functions...

You can check connect-livereload on how it adds a script to any html output.

One more solution from here:

expressApp.use(function (req, res, next) {    req.on("end", function () {        console.log('on request end');    });    next();});

Your lack of code makes it really hard to answer your question, but you could use something like

Express 4.0:router.use('/path', function (req, res) {    // Modify req});

.use on a route will parse that before continuing on to the actual route so if somebody submitted a form or something, it will hit the .use before it goes to the .post or .get

Or you can do

Express 4.0:app.use(function (req, res) {    // Modify Req    if (req.body.hasOwnProperty('some_form_name')) {       // Do Somthing    }});

Which is the same thing, but it will be called before every request for every route.

Not sure if this answers your question but I think this might be what you're looking for?