Question

What’s the proper way to use custom callbacks with express.js functions?

Here’s an example:

//routes/reset.js

user.save(function(err){
  if ( err ) return next(err);
  reset.send_reset_email(req, res, user, function(req, res){
    req.flash('info', 'Check your email for a link to reset your password.');
    res.redirect('/');
  });
});

What signature should I use for reset.send_reset_email for this to work correctly?

This is what I have:

exports.send_reset_email = function(req, res, user, next){
  //send email
  transport.sendMail(options, function(err, responseStatus) {
     if (err) { 
      console.log(err);
    } else { 
      next(req, res);
     //do I need to explicitly pass req, res here?
     //is next() reserved word here?
    } 
  });

});

Do I need to explicitly pass req, res here?
is next() reserved word here?

Answer 1

next() accepts an error or another route and is usualy called to continue with the next middleware.

in your send_reset_email function your next() isn’t express’s next() because you pass in function(req,res) and not next, pass in your own callback instead to handle the outcome of your sendmail function.

user.save(function(err){
  if (err) return next(err) // if thats express's next()
  reset.send_reset_email(req, res, user, function(err, data){
    if(err) {
      // send err msg
    } else {
      req.flash('info', 'Check your email for a link to reset your password.');
      res.redirect('/');
    }
  });
});


xports.send_reset_email = function(req, res, user, cb){
  //send email
  transport.sendMail(options, function(err, responseStatus) {
     if (err) return cb(err)
     cb(null,responseStatus)
  })
})