In order to receive key events, we'll create one function called onKeyUp and another called onKeyDown, then use a bit of jQuery magic to bind them to the appropriate events.
Then, on our way through the draw function, we'll check to see if either arrow is pressed down, and move the paddle accordingly.
Now that we've got a working paddle, animation, and a bouncing ball, we've got something close to a game coming together.
On the next page, we'll move support for the keyboard into the library and add support for the mouse in a very similar manner.