Assuming your game is an action game where the pages are not reloaded between moves:
* If you're targeting a PC/iPad/iPhone and your game is real-time action, I suggest you start using the Canvas object.
* If you are targeting Android, don't use HTML (It's slow and unpredictable where graphics are concerned).
* Use an IDE, I personally recommend Webstorm, Never develop from Notepad (or emacs). Thats just sloppy.
* Use Chrome/Safari for debugging (depends if you're on PC/Apple) [In chrome press ctrl+shift+j to start the debugger]..