how variable scope works in jquery?

var change = 1;

$("#game").click(function (e) {
    if (change == 1) {
        var data = $(e.target).closest("td").text();
        var p1 = $("#player1").val();
        var p1_value = p1 + data;
        $("#player1").val(p1_value);
        change = 2;
    } else(change == 2) {
        var data = $(e.target).closest("td").text();
        var p2 = $("#player2").val();
        var p2_value = p2 + data;
        $("#player2").val(p1_valu开发者_如何学Goe);
        change = 1;
    }

});

Is it the write way to write? BTW here it is not going to the else loop.

---

JavaScript has only function scope, not "curly bracket scope". If you want to be very correct, you would put all the declarations at the top of the function:

$("#game").click(function(e) {
    var data = '',
        p1 = '',
        p1_value = '',
        p2 = '',
        p2_value = '';

        if (change == 1) {
            data = $(e.target).closest("td").text();
            p1 = $("#player1").val();
            p1_value = p1 + data;
            $("#player1").val(p1_value);
            change = 2;
        }
        else if (change == 2) { // you forgot `if`
            data = $(e.target).closest("td").text();
            p2 = $("#player2").val();
            p2_value = p2 + data;
            $("#player2").val(p1_value);
            change = 1;
        }
});

At least JSLint complains about data being already defined.

But you can optimize (and shorten!) your function in another way:

$("#game").click(function(e) {
    var $player = $('#player' + change);
    $player.val($player.val() + $(e.target).closest("td").text());
    change = (change === 1) ? 2 : 1;
}

---

Your else should be an else if if you intend to use the condition:

if (change == 1) {
    // ...
} else if(change == 2) {
    // ...
}

As perhaps a better alternative, you can use jQuery's .toggle(), and pass it two functions which alternate on clicks.

$("#game").toggle(function(e) {
            var data = $(e.target).closest("td").text();
            var p1 = $("#player1").val();
            var p1_value = p1 + data;
            $("#player1").val(p1_value);
 }, function(e) {
            var data = $(e.target).closest("td").text();
            var p2 = $("#player2").val();
            var p2_value = p2 + data;
            $("#player2").val(p1_value);
 });