node.js - before and after hooks for a request in express (to be executed before any req and after any res)

Question

ExpressJS middleware req, res, next have hooks like .on and .pipe.

But I'm looking for hooks for the app.get and app.post methods.

Answer 1

app.use() and middleware can be used for "before" and a combination of the 'close' and 'finish' events can be used for "after."

app.use(function (req, res, next) {
    function afterResponse() {
        res.removeListener('finish', afterResponse);
        res.removeListener('close', afterResponse);

        // action after response
    }

    res.on('finish', afterResponse);
    res.on('close', afterResponse);

    // action before request
    // eventually calling `next()`
});

app.use(app.router);

An example of this is the logger middleware, which will append to the log after the response by default.

Just make sure this "middleware" is used before app.router as order does matter.