JQuery 不会在 $(document).change() 上执行
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JQuery does not execute on $(document).change()
提问by Theomax
I need to make some JQuery execute when the page/document has changed - in this case, when a div with a specific CSS class is displayed.
当页面/文档发生变化时，我需要执行一些 JQuery - 在这种情况下，当显示具有特定 CSS 类的 div 时。
I have the following JQuery code:
我有以下 JQuery 代码：
<script>
$(document).change(function () {
if ($('.validation_errors').length) {
alert("test");
}
}
</script>
However, it does not execute and display the alert. Am I missing something here?
但是，它不会执行和显示警报。我在这里错过了什么吗？
回答by noj
Change is only for input, textarea or select elements. Instead you need to bind a function to the DOMSubtreeModifiedmutation event:
更改仅适用于 input、textarea 或 select 元素。相反，您需要将函数绑定到DOMSubtreeModified突变事件：
$(document).bind('DOMSubtreeModified', function () {
if ($('.validation_errors').length) {
alert("test");
}
});
EDIT: If your target browsers support it, you should use a MutationObserverinstead.
编辑：如果您的目标浏览器支持它，您应该改用MutationObserver。
回答by Josh Davenport
You can't monitor changes in the DOM is this manner. Quote from the jQuery docs:
您不能以这种方式监视 DOM 中的更改。引用自 jQuery 文档：
The change event is sent to an element when its value changes. This event is limited to elements, boxes and elements. - http://api.jquery.com/change/
当元素的值发生变化时，将更改事件发送到元素。此事件仅限于元素、框和元素。- http://api.jquery.com/change/
If you're looking to execute code when there is a DOM change, you may need to either set up and interval which checks the DOM or use this techniqueprovided by a poster on the jQuery forums.
如果您希望在 DOM 更改时执行代码，您可能需要设置和间隔检查 DOM，或者使用jQuery 论坛上的海报提供的这种技术。
There is the DOMSubtreeModifiedevent, but it is scarcely available in current browsers, so I personally wouldn't recommend its use. See this stackoverflow answerfor further details on that
有这个DOMSubtreeModified事件，但它在当前浏览器中几乎不可用，所以我个人不推荐使用它。有关更多详细信息，请参阅此 stackoverflow 答案
回答by Shannon
Your syntax is wrong too buddy! If you're going to do it, do it within document ready, .change is very limited and wont fire on a new page.
哥们你的语法也错了！如果您打算这样做，请在准备好的文档内进行，.change 非常有限，不会在新页面上触发。
$(document).ready(function(){
if($('.classOrId').length){
//do something if it exists
};
});
