jQuery hasClass()
jQuery hasClass()方法用于检查所选元素是否具有指定的类名。如果指定的类存在于任何选定的元素中,则返回TRUE,否则返回FALSE。
语法 :
$(selector).hasClass(classname)
jQuery hasClass()方法的参数
参数
说明
className
这是强制性参数。它指定要在所选元素中搜索的CSS类的名称。
jQuery hasClass()方法的示例
让我们以一个示例来演示jQuery hasClass()方法。
<!DOCTYPE html> <html> <head> <script src="/ajax/libs/jquery/1.11.3/jquery.min.js"></script> <script> $(document).ready(function(){ $("button").click(function(){ alert($("p").hasClass("intro")); }); }); </script> <style> .intro { font-size: 150%; color: Blue; } </style> </head> <body> <h1>Look here, I am a heading.</h1> <p class="intro">This is a paragraph.</p> <p>This is also a paragraph.</p> <button>Click here to check if any p element have an "intro" class?</button> </body> </html>
输出:
Look here, I am a heading.
This is a paragraph.
This is also a paragraph.
Click here to check if any p element have an "intro" class?
jQuery hasClass()方法示例2
让我们再举一个示例来演示jQuery hasClass()方法。
<!DOCTYPE html> <html> <head> <title>The Selecter Example</title> <script type="text/javascript" src="/ajax/libs/jquery/2.1.3/jquery.min.js"> </script> <script type="text/javascript" language="javascript"> $(document).ready(function() { $("#result1").text( $("p#pid1").hasClass("red") ); $("#result2").text( $("p#pid2").hasClass("red") ); }); </script> <style> .red { color:red; } .blue { color:blue; } </style> </head> <body> <p class="red" id="pid1">This is first paragraph.</p> <p class="blue" id="pid2">This is second paragraph.</p> <div id="result1"></div> <div id="result2"></div> </body> </html>
输出:
This is first paragraph.
This is second paragraph.
注意: 第一个条件为true,第二个条件为false。如果我们设置第二段的类名是" blue"?那么这两个条件都将成立。
jQuery hasClass()示例3
<!DOCTYPE html> <html> <head> <title>The Selecter Example</title> <script type="text/javascript" src="/ajax/libs/jquery/2.1.3/jquery.min.js"> </script> <script type="text/javascript" language="javascript"> $(document).ready(function() { $("#result1").text( $("p#pid1").hasClass("red") ); $("#result2").text( $("p#pid2").hasClass("blue") ); }); </script> <style> .red { color:red; } .blue { color:blue; } </style> </head> <body> <p class="red" id="pid1">This is first paragraph.</p> <p class="blue" id="pid2">This is second paragraph.</p> <div id="result1"></div> <div id="result2"></div> </body> </html>
输出:
This is first paragraph.
This is second paragraph.
这两个条件都成立。
jQuery hasClass()示例4
<!DOCTYPE html> <html> <head> <script src="/ajax/libs/jquery/1.11.1/jquery.min.js"></script> <script> $(document).ready(function() { $(".btn").click(function(){ var className = $(this).attr("id"); $("ul li").each(function() { if ($(this).hasClass(className)) { $(this).fadeTo('slow', 0.0).fadeTo('slow', 1.0); } }); }); }); </script> <style> ul{ font-family: monospace; font-size: 15px; font-family: monospace; font-style: normal; font-size-adjust: none; width:200px; padding:0px; } ul li{ background-color:#7fffd4; width:100px; margin:5px; padding:5px; list-style-type:none; width:200px; } </style> </head> <body> <h1>jQuery .hasClass() function Example</h1> <ul> <li class="red">Red</li> <li class="green">Green</li> <li class="green red">Green Red</li> <li class="blue">Blue</li> </ul> <input type="button" class="btn" value="Red Class" id="red"> <input type="button" class="btn" value="Green Class" id="green"> <input type="button" class="btn" value="Blue Class" id="blue"> <input type="button" class="btn" value="No Matching Class" id="noclass"> </body> </html>
输出: