添加类：addClass
删除类：removeClass
判断类是否存在：hasClass
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <title>Title</title> <script src="jquery-1.11.1.js"></script> <style> div { width: 100px; height: 100px; border: 1px solid #ccc; float: left; } .box1 { margin-right: 10px; } .box2 { margin-left: 10px; } .show { background-color: red; } </style> <script src="jquery-1.11.1.js"></script> <script> $(function () { $(".box2").addClass("show"); $(".box1").removeClass("show"); console.log($("box1").hasClass("show")); }); </script> </head> <body> <div class="box1"></div> <div class="box2"></div> </body> </html>