我的问题是一个奇怪的一个，因为在标题中描述。这里的code：

My problem is a weird one, as described in the title. Here's the code:

案例1：

    var first = $.ajax({ // about 500ms request
        url: myUrl
        success: function() { console.log(1); }
    });

    var second = $.ajax({ // about 200 ms request
        url: myUrl
        success: function() { console.log(2); }
    });


    $.when(first, second).done(function() { console.log(3); });

日志2，1，3，所有的好，正是我想要的。

Logs 2, 1, 3. All good, just what I wanted.

案例2：

    var first = $.ajax({ // about 500ms request
        url: myUrl
        success: function() { console.log(1); }
    });

    var second = $.ajax({ // about 200 ms request
        url: myUrl
        success: function() { console.log(2); }
    });

    function logthree() {
        console.log(3);
    }


    $.when(first, second).done(logthree());

日志3，2，1，这是一个问题。该logthree（）函数应该只一次，第一和第二的决心执行。

Logs 3, 2, 1, which is a problem. The logthree() function should only execute once first and second resolve.

为什么会出现这种情况？如何使用第2种情况没有任何问题？

Why does this happen? How can I use Case 2 without any problems?

注：同样的事情发生，如果第一和第二是功能，它们返回$就

Note: same thing happens if first and second are functions and they return an $.ajax.

注：同样的事情发生，如果第一和第二都是$不用彷徨

Note: same thing happens if first and second are both $.get.

推荐答案

更​​改为：

$.when(first, second).done(logthree);

正在执行 logthree（）并通过返回的结果为 .done（）。你需要传递一个函数引用 .done（）这仅仅是 logthree 没有括号。当您添加括号，即指示JS跨preTER立即执行。这是一个常见的​​错误。

You are executing logthree() and passing the return result to .done(). You need to pass a function reference to .done() which is just logthree without the parens. When you add parens, that instructs the JS interpreter to execute it immediately. This is a common mistake.