Talking about game development in HTML5, you need to know that building a game from scratch is not always a good idea. You have to look around to find some game engine or framework that will let you comfortable which will speed up the development time. Game engines are just one more level of abstraction that take care of a few of the more tedious tasks of game development. Most take care of asset loading, input, physics, audio, sprite maps and animation, but they vary quite a bit. Some engines are pretty barebones, while some go as far as including a 2D level editor and debug tools.