注意下面两个的区别:
$(".role-developer.role-designer").css("color","red");
$(".role-developer .role-designer").css("background","#ff0");
<!doctype html> <html> <head> <meta charset="utf-8"> <title></title> <script src="http://code.jquery.com/jquery-1.7.2.min.js"></script> <script type="text/javascript"> $(function(){ $("li").click(function(){ $(".role-developer.role-designer").css("color","red"); $(".role-developer .role-designer").css("background","#ff0"); }); }); </script> </head> <body> <h3>用多个class选择元素</h3> <ul> <li class="role-developer role-designer">Mark <ul> <li class="role-developer">mmmm</li> <li class="role-developer">mmmmm2</li> </ul> </li> <li class="role-developer ">Simon <ul> <li class="role-developer">mmmm</li> <li class="role-designer">mmmmm2</li> </ul> </li> <li class="role-developer role-manager">Kevin <ul> <li class="role-designer">mmmm</li> <li class="role-designer">mmmmm2</li> </ul> </li> </ul> </body> </html>