const alphabet = 'abcdefgh' let squares = document.getElementsByClassName('square') sync_board() let previously_highlighted_squares = ['dummy'] for (let i = 0; i < squares.length; i++) { squares[i].addEventListener('click', () => { let square = [] let id = squares[i].id square.push(8 - id.charAt(1)) square.push(id.charAt(0).charCodeAt(0) - 97) let moves = move(board, square[0], square[1], to_move) for (let i = 0; i < previously_highlighted_squares.length; i++) { let prev = document.getElementById(previously_highlighted_squares[i]) prev.classList.remove('highlight') } for (let i = 0; i < moves.length; i++) { document.getElementById(`${alphabet[moves[i][1]]}${8 - moves[i][0]}`).classList.add('highlight') previously_highlighted_squares.push(`${alphabet[moves[i][1]]}${8 - moves[i][0]}`) } }) }