Putting it all together
Draw a square on the screen, using a square
object to track state.
Make it move to the right across the screen.
When it reaches the right edge, it should reverse
direction and move to the left.
When it reaches the left edge, it should reverse
direction and move to the right.
Reminder: You can get the canvas width from ctx.
A particular slide catching your eye?
Clipping is a handy way to collect important slides you want to go back to later.