Promises are almost always better than callbacks, so can someone replace almost all callbacks with Promises.
Adding promises would actually shorten the functions by removing the error, and success callbacks, converting loadImage('test.png', success, err) to loadImage('test.png')
ALSO, I feel like that should keep the whileLoading callbacks, or any other repeated callback since those are needed and may not even work for promises! (It would be really cool if you could send values while a promise was pending, so you could send the percentage that a file has loaded in before it was finished or something. like that… )