You need to define where the script runs.
Board squares are div elements with classes like square-<file><rank> and pieces as div with piece-<type> . tampermonkey chess script
; function getBestMove(fen, depth=18) stockfish.postMessage(`position fen $fen`); stockfish.postMessage(`go depth $depth`); You need to define where the script runs
on the Greasy Fork page. Tampermonkey will open a new tab showing the code. and pieces as div with piece-<