There may be situations in the code where different operations are performed based on whether the element exists, so it is necessary to determine whether the specified element exists.
Use $(selector) to get the set of matching elements, and the length attribute of the set of matching elements can get the number of matching elements in the set, so as long as you determine whether the length attribute value is zero, you can determine whether the element exists. The code example is as follows:
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>脚本之家</title>
<script type="text/javascript" src="mytest/jQuery/jquery-1.8.3.js"></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>脚本之家</li>
<li class="mytest">div+css教程</li>
</ul>
<button id="check">点击检测</button>
</body>
</html>
If the number of elements in the collection is greater than zero, then the element exists, otherwise the specified element does not exist.
The above is the entire content of this article, I hope you all like it
jquery实现多少秒后隐藏图片Apr 20, 2022 pm 05:33 PM实现方法：1、用“$("img").delay(毫秒数).fadeOut()”语句，delay()设置延迟秒数；2、用“setTimeout(function(){ $("img").hide(); },毫秒值);”语句，通过定时器来延迟。
axios与jquery的区别是什么Apr 20, 2022 pm 06:18 PM区别：1、axios是一个异步请求框架，用于封装底层的XMLHttpRequest，而jquery是一个JavaScript库，只是顺便封装了dom操作；2、axios是基于承诺对象的，可以用承诺对象中的方法，而jquery不基于承诺对象。
jquery怎么修改min-height样式Apr 20, 2022 pm 12:19 PM修改方法：1、用css()设置新样式，语法“$(元素).css("min-height","新值")”；2、用attr()，通过设置style属性来添加新样式，语法“$(元素).attr("style","min-height:新值")”。
jquery怎么在body中增加元素Apr 22, 2022 am 11:13 AM增加元素的方法：1、用append()，语法“$("body").append(新元素)”，可向body内部的末尾处增加元素；2、用prepend()，语法“$("body").prepend(新元素)”，可向body内部的开始处增加元素。
jquery怎么删除div内所有子元素Apr 21, 2022 pm 07:08 PM删除方法：1、用empty()，语法“$("div").empty();”，可删除所有子节点和内容；2、用children()和remove()，语法“$("div").children().remove();”，只删除子元素，不删除内容。
jquery中apply()方法怎么用Apr 24, 2022 pm 05:35 PM在jquery中，apply()方法用于改变this指向，使用另一个对象替换当前对象，是应用某一对象的一个方法，语法为“apply(thisobj,[argarray])”；参数argarray表示的是以数组的形式进行传递。
jquery怎么去掉只读属性Apr 20, 2022 pm 07:55 PM去掉方法：1、用“$(selector).removeAttr("readonly")”语句删除readonly属性；2、用“$(selector).attr("readonly",false)”将readonly属性的值设置为false。
jquery on()有几个参数Apr 21, 2022 am 11:29 AMon()方法有4个参数：1、第一个参数不可省略，规定要从被选元素添加的一个或多个事件或命名空间；2、第二个参数可省略，规定元素的事件处理程序；3、第三个参数可省略，规定传递到函数的额外数据；4、第四个参数可省略，规定当事件发生时运行的函数。
Hot AI Tools
Undresser.AI Undress
AI-powered app for creating realistic nude photos
AI Clothes Remover
Online AI tool for removing clothes from photos.
Undress AI Tool
Undress images for free
Clothoff.io
AI clothes remover
AI Hentai Generator
Generate AI Hentai for free.
Hot Article
Hot Tools
EditPlus Chinese cracked version
Small size, syntax highlighting, does not support code prompt function
VSCode Windows 64-bit Download
A free and powerful IDE editor launched by Microsoft
Dreamweaver Mac version
Visual web development tools
MinGW - Minimalist GNU for Windows
This project is in the process of being migrated to osdn.net/projects/mingw, you can continue to follow us there. MinGW: A native Windows port of the GNU Compiler Collection (GCC), freely distributable import libraries and header files for building native Windows applications; includes extensions to the MSVC runtime to support C99 functionality. All MinGW software can run on 64-bit Windows platforms.
PhpStorm Mac version
The latest (2018.2.1) professional PHP integrated development tool
