I think what the person meant by 'passing around' was something like this (in plain express):
app.get('/kittens', function(req, res) {
db.doAthing(req);
updateSomethingElse(res);
upvoteThisAnswer(res);
});
That is, passing around the two variables beyond the first function. This is bad because it becomes increasingly difficult to figure out where the call actually ends. One little res.end(500)
in updateSomethingElse
can cause the whole house of cards to come tumbling down.
It's perfectly ok (in fact, standard to the point of being the default in express) to declare that callback elsewhere (usually the /routes
directory of your project.)
// app.js
var user = require('./routes/user')
, kittens = require('./routes/kittens');
// express stuff...
app.get('/settings', user.getSettings);
app.get('/fur', kittens.shed);
Then, in routes/user.js
:
exports.getSettings = function(req, res) {
// Note how we're passing around properties of req/res, not the objects themselves.
db.getUserSettings(req.user.id).then(function(settings) {
res.render('settings', settings);
});
};