Вы можете пойти с этим подходом
winnerCombs = [
[1,2,3],
[4,5,6],
[7,8,9],
[1,4,7],
[2,5,8],
[3,6,9],
[3,5,7],
[1,5,9]
]
const checkWinner = player => {
return winnerCombs.some(comb => comb.every(c => $("#item" + c).hasClass(player) ))
}
isWinnerX = checkWinner(".winnerX") // return true if winner is Player X
isWinnerY = checkWinner(".winnerY") // return true if winner is Player Y