So, only do \"res.render\" when you are sure that everything has finished, right? Because it ends the request and shoots out a webpage.
If you don't provide a callback to res.render(view[, options[, fn]])
it will automatically give a response with 200 HTTP Status and Content-Type: text/html
res.render('view', {}, function() {
while (true); // should block
});
res.render(view[, options[, fn]])
Render view with the given options and optional callback fn. When a callback function is given a response will not be made automatically, however otherwise a response of 200 and text/html is given.
express.js guide