有人可以解释什么= $();在jQuery中意味着什么? [英] Can someone explain what = $(); means in jQuery?

问题描述

我正在查看的某些代码中包含以下内容:

I have the following in some code I am looking at:

    // Save an empty jQuery in our cache for now.
    dialogs[id] = $();

任何人都可以解释它的意思.我对这个概念一无所知.谢谢

Can anyone explain what it means. I have no idea about this concept. thanks

更新:

还有更多代码:

    var loadAndShowDialog = function (id, link, url) {
    var separator = url.indexOf('?') >= 0 ? '&' : '?';

    // Save an empty jQuery in our cache for now.
    dialogs[id] = $();

    // Load the dialog with the content=1 QueryString in order to get a PartialView
    $.get(url + separator + 'content=1')
        .done(function (content) {
            dialogs[id] = $('<div class="modal-popup">' + content + '</div>')
                .hide() // Hide the dialog for now so we prevent flicker
                .appendTo(document.body)
                .filter('div') // Filter for the div tag only, script tags could surface
                .dialog({ // Create the jQuery UI dialog
                    title: link.data('dialog-title'),
                    modal: true,
                    resizable: true,
                    draggable: true,
                    width: link.data('dialog-width') || 300
                })
                .find('form') // Attach logic on forms
                    .submit(formSubmitHandler)
                .end();
        });
};

我仍然看不到第一行的要点.有人向我解释说，它创建了一个空的jquery对象，但我不明白为什么.

I still cannot see the point of the first line. It's been explained to me that it creates an empty jquery object but I can't understand why.

推荐答案

其他答案正确.调用$()会创建一个空的jQuery对象.

The other answers are correct; calling $() creates an empty jQuery object.

但是，在您现有代码的上下文中，似乎不需要它.用$()初始化的dialogs[id]变量仅重新分配了另一个值，而不使用其原始值.

In the context of your existing code, though, it seems that it's not needed. The dialogs[id] variable, which was initialized with $() is only reassigned with another value, without using its original value.

需要注意的一件事是，在完成AJAX调用期间，随后会给dialogs[id]变量赋予另一个值 ，这意味着该变量可以在您的其他位置使用异步操作$.get正在进行时的代码.它可能在函数内部，但是使用var的作用域不正确，因此有点可疑.

One thing to take note of, however, is that the dialogs[id] variable is subsequently given another value during the completion of an AJAX call, which means that it may be used somewhere else in your code while the asynchronous operation $.get is going on. It may be inside a function, but it's not properly scoped using var, so that's a bit dubious.

不过，根据它的外观(并基于其使用方式)，我敢打赌它不是，并且您可能会正确地认为$()初始化是完全不必要的.

From what it looks like (and based on how its used) though, I'm willing to bet that it's not, and you may be correct that the $() initialization is completely unnecessary.

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