将变量的值推入数组将返回Void 0？

Question

I'm creating a simple tic-tac-toe game and I'm currently trying to store the user's checks into variables. The problem is, with my current code the xMoves and oMoves arrays are returning Void 0. What's wrong with this code? http://jsfiddle.net/Z6StP/

var storeMoves = function () {
    if (currentPlayer === X) {
        xMoves.push(cellTracker);
    } else if (currentPlayer === O) {
        oMoves.push(cellTracker);
    }
};

Answer 1

void 0; is just another way of representing the undefined value.

The .push() methods are not returning void 0 . They return the new Array length.

What you're seeing in the console is the Array with void 0 (or undefined ) inside. That's because you're pushing cellTracker into the Arrays, which is never assigned a value.

You do have an assignment to cellTracker , but that's a local variable. Remove the var before it, and you'll be assigning to the outer one.

/*var*/ cellTracker = $(this).attr('id');

Answer 2

Because you define again the variable cellTracker inside the click function of the td's . Remove the definition and use the already defined variable and it will work.

Like:

$('td').one('click', function () {
    turnCount += 1;
    setCurrentPlayer();
    $(this).text(currentPlayer);
    cellTracker = $(this).attr('id');
    storeMoves();
    console.log(turnCount, xMoves, oMoves);
});

Fiddle: http://jsfiddle.net/IrvinDominin/Z6StP/1/