functions in functions nodejs

Question

I want to get the klout score using a screen name (twitter).

I did this. I know it doesn't work like that, but I don't know how it should work.

function get_klout(screenName){
  klout.getKloutIdentity(screenName, function(error, klout_user) {
    klout.getUserScore(klout_user.id, function(error, klout_response) {
       return Math.round(klout_response.score);
    });
  });
}

I want my function to return this number Math.round(klout_response.score);

Answer 1

function get_klout(screenName) {

  klout.getKloutIdentity(screenName, function(error, klout_user) {

    klout.getUserScore(klout_user.id, function(error, klout_response) {

       return Math.round(klout_response.score);
    });
  });
}

Your function is async, so you can't just assign what it returns to a variable because you will just assign undefined: var result = get_klout('foo'); // undefined

what you can do is:

1. using async functions in node 8+
2. using Promises
3. using callbacks:

function get_klout(screenName, done) {

  klout.getKloutIdentity(screenName, function(error, klout_user) {

    klout.getUserScore(klout_user.id, function(error, klout_response) {

        done(Math.round(klout_response.score));
    });
  });
}

get_klout('foo', function(response) {
  console.log(response);
});

just a note: In node is a common pattern implementing the error first callback and you should have a look on it because it's the traditional and more used way to handle errors: http://fredkschott.com/post/2014/03/understanding-error-first-callbacks-in-node-js/