为什么turnCount没有更新？(Why isn't turnCount updating?)

 我正在尝试创建一个井字游戏。 你可以想象我只是在我的html中有一个包含三行和九个数据单元的表，所以我不打算发布它，但由于某种原因我在我的脚本（更新turnCount的那个）中的第一个函数没有'似乎在做任何事情。 
 
var X = 'X';
var O = 'O';
var currentPlayer;
var turnCount = 0;

$(document).ready(function () {
    $('td').click(function () {
        turnCount += 1;
    });
});

var setCurrentPlayer = function () {
    if (turnCount % 2 === 0) {
        currentPlayer = O;
    } else {
        currentPlayer = X;
    }
};
setCurrentPlayer();

$(document).ready(function () {
    $('td').click(function () {
        $(this).text(currentPlayer);
    });
});

I'm trying to create a tic-tac-toe game. As you can imagine I simply have a table with three rows and nine data-cells in my html so I won't bother posting that, but for some reason the first function I have in my script(the one that updates turnCount) doesn't seem to be doing anything. 
 
var X = 'X';
var O = 'O';
var currentPlayer;
var turnCount = 0;

$(document).ready(function () {
    $('td').click(function () {
        turnCount += 1;
    });
});

var setCurrentPlayer = function () {
    if (turnCount % 2 === 0) {
        currentPlayer = O;
    } else {
        currentPlayer = X;
    }
};
setCurrentPlayer();

$(document).ready(function () {
    $('td').click(function () {
        $(this).text(currentPlayer);
    });
});

原文：https://stackoverflow.com/questions/16997089