How to determine whether a specified class exists in jquery-JS Tutorial-php.cn

How to determine whether a specified class exists in jquery

青灯夜游

Release： 2021-11-25 11:49:26

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Method: 1. Use the "$(element).hasClass("class name")" statement to check whether the specified class exists. If it exists, return "true"; 2. Use "$(element).attr" ("class")" statement obtains the value of the class attribute. If the value is equal to the class name to be checked, the specified class exists.

How to determine whether a specified class exists in jquery

The operating environment of this tutorial: windows7 system, jquery1.10.2 version, Dell G3 computer.

jquery determines whether the specified class exists

Method 1: Use the hasClass() method

The hasClass() method checks whether the selected element contains the specified class name. This method returns "true" if the selected element contains the specified class.

<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<script src="js/jquery-1.10.2.min.js"></script>
		<script>
			$(document).ready(function(){
				$("button").click(function(){
					var a=$("p").hasClass("intro");
					if(a){
						alert("指定类存在");
					}else{
						alert("指定类不存在");
					}
				});
			});
			</script>
		<style type="text/css">
			.intro {
				font-size: 120%;
				color: red;
			}
		</style>
	</head>
	<body>

		<h1>这是一个段落标题</h1>
		<p class="intro">这是一个段落</p>
		<p> 这是另外一个段落</p>
		<button>是否有 p 元素使用了 "intro" 类?</button>

	</body>
</html>

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How to determine whether a specified class exists in jquery

Method 2: Use the attr() method

attr() method can return the attribute value of the selected element.

You can use the attr() method to get the value of the class attribute. If the attribute value is equal to the class name that needs to be checked, the specified class exists.

<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<script src="js/jquery-1.10.2.min.js"></script>
		<script>
			$(document).ready(function(){
				$("button").click(function(){
					var a=$("p").attr("class");
					if(a=="intro1"){
						alert("指定类存在");
					}else{
						alert("指定类不存在");
					}
				});
			});
			</script>
		<style type="text/css">
			.intro {
				font-size: 120%;
				color: red;
			}
		</style>
	</head>
	<body>

		<h1>这是一个段落标题</h1>
		<p class="intro">这是一个段落</p>
		<p> 这是另外一个段落</p>
		<button>是否有 p 元素使用了 "intro1" 类?</button>

	</body>
</html>

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How to determine whether a specified class exists in jquery

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