javascript: pass return value in callback function

Please help me understand this:

I have an object self.domainSettings() which has a save method. The save returns the result which I want to use in callback function to populate success or error message. I am using following code:

self.domainSettings().save(function(data){
    console.log('in here');
    console.log(data);
    console.log('outta here');
 }());


function save(){
  return 'success';
};

When I do console.log(data) is it guaranteed that the save has finished executing ? Also it says data is undefined because the return value of save is not getting passed to callback function I guess. How do I get that ?

Answer

You have to pass callback in save() in order to access the result from a callback.

function save(fn){
  return fn('success');
};