2D Canvas: low-level, 2D graphics rendering - HTML5 in Action - page 263

Listing 6.17. game.js—Ball and brick upgrades
When a level up occurs, everything except the Hud needs to be updated with a new method
called Game.levelUp() . Problem is, allowing players to level up past 5 will cause
your game's bricks to take over the screen. To prevent brick overflow, you need to add a
Game.levelLimit() method and modify the Bricks.init() logic to use it. Once
you've inserted the code from the next listing, Canvas Ricochet can be played with mul-
tiple levels.