have you handled the key repeat? the controls are broken.
What behavior do you get? While you're in the wall at the start of the game, a single key press should move one space (holding does nothing), and when you're outside of the wall, holding a key should move the character until you let go of the key.
I've tested it in Firefox on my own machines and it works as expected, so it would be great to know what problem you're encountering in more detail so I can fix it!