How to declare callback like Parse does?

Question

Usually, I declare a function with success and fail callbacks as follow

function yoyoyo(param, successCallback, failCallback) {
  // do something with param
  // ...
  if (success) {
    successCallback('success');
  } else {
    failCallback('fail');
  }
}

then I will use it like this

yoyoyo('abc', function(success) {
  console.log(success);
}, function(err) {
  console.log(err);  
});

BUT, when I look into Parse Javascript Guide, they guide me to use the function like this (i.e. merge success and fail callbacks in one object?)

var GameScore = Parse.Object.extend("GameScore");
var query = new Parse.Query(GameScore);
query.get("xWMyZ4YEGZ", {
  success: function(gameScore) {
    // The object was retrieved successfully.
  },
  error: function(object, error) {
    // The object was not retrieved successfully.
    // error is a Parse.Error with an error code and message.
  }
});

How can I declare my function with success and fail callbacks like parse does?

Answer 1

You would just change your function to accept a callbacks arg (call it whatever you want) and then access the handlers off that object:

function yoyoyo(param, callbacks) {
  // do something with param
  // ...
  if (success) {
    callbacks.success('success');
  } else {
    callbacks.error('fail');
  }
}

then you would call it with:

yoyoyo('abc', {
    success: function(status) { 
    },
    error: function(status) {
    }
});

Note though, that your code should check to ensure that the object passed in has both of the methods before attempting to call them.