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How does jQuery detect whether an element exists? -PHP Chinese website Q&A-How does jQuery detect whether an element exists? -PHP Chinese website Q&A
Let’s take a look and learn.
使用$(selector)可以获得匹配元素集合，而匹配元素集合的length属性可以获得集合中匹配元素的个数，所以只要判断length属性值是否为零，就可以判断元素是否存在。代码实例如下:
<!DOCTYPE html> <html> <head> <meta charset="utf-8"> <title>PHP中文网</title> <script type="text/javascript" src="mytest/jQuery/jquery-1.8.3.js?1.1.9"></script> <script type="text/javascript"> $(document).ready(function(){ $("#check").click(function(){ if($(".mytest").length>0){ alert("此元素存在"); } }) }) </script> <body> <ul> <li>太阳出来了</li> <li>PHP中文网</li> <li class="mytest">p+css教程</li> </ul> <button id="check">点击检测</button> </body> </html>如果集合中元素的数量大于零，那么元素存在，否则指定元素不存在。