判断jQuery是否没有找到任何元素 [英] Determining whether jQuery has not found any element

问题描述

我正在使用 jQuery 的选择器，尤其是 id 选择器:

I'm using jQuery's selectors, especially id selector:

$("#elementId")...

我应该如何判断 jQuery 是否找到了该元素?即使具有指定 id 的元素不存在，下一条语句给我:[object Object]

How should I determine whether jQuery has found the element or not? Even If the element with the specified id doesn't exist the next statement give me: [object Object]

alert($("#idThatDoesnotexist"));

推荐答案

$('#idThatDoesnotexist').length 就是你要找的.(如果什么都没找到，这将 === 0.)所以你的条件语句应该是:

$('#idThatDoesnotexist').length is what you're looking for. (If it finds nothing, this will === 0.) So your conditional statement should probably be:

if($('#id').length) { /* code if found */ } else { /* code if not found */ }

您会从该警报返回一个对象，因为 jQuery(几乎)在您使用它时总是返回jQuery 对象"，它是 jQuery 发现的允许方法链接的元素的包装器.

You're getting an object returned from that alert because jQuery (almost) always returns the "jQuery object" when you use it, which is a wrapper for the elements jQuery's found that permits method chaining.

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