I settled for the second trick newcomers learn -- forking the Queen and the Rook with the Knight. Easy win being up a Rook and Pawn to a Knight, with the black's King uncastled and in the open.

I expected it to play like Ed's Chess on DOS, which I always had trouble beating. IIRC that engine looks 3-4 moves ahead usually, but 6-7 moves ahead when it needs to. No idea how big the equivalent JS would be.

Looking ahead more moves requires zero more code -- depth is a loop variable.

Well the deeper you look, the more clever you need to be about pruning your branches and exploring the search space, so I would guess it does require more code.