A simple accumulator object.
If several things need to be completed before something else happens, this will prevent "Christmas-tree" code.
Simply create an accumulator with two arguments: an array of object property names that will be used to store your data while it accumulates and a callback to be executed upon completion.
In the callback of each of the tasks that need to be completed, after you assign the result to the appropriate property, simply call "finalize".
This will check the properties to see if they are defined. If all properties are defined at the time this method is called, the accumulator's callback is initiated.