nodejs / express: does calling next() automatically return the function it is called from?

Question

Just wanted to get this out of my head:

when dealing with routing in Express/ Nodejs I want to know if calling next() always returns the function it is called from? Consider:

app.get('/users/:id?', function(req, res, next){
   //just as as example
   var err = doValidation(req);
   if (err) {
       next(err);
   } 
   next(); //will this ever be called?
});

In case of an error, will the second next() ever be called, or will a call for the first next(err) (automagically) return the function it is called from?

Answer 1

Calling next() doesn't halt execution, but return does, so return next() does return.

Answer 2

Yes, if an error, both will be called. You want to do:

if(err) {
  return next(err);  
}