此函数必须返回一个或多个空格分隔的class名,如果第二个参数是callback,那么需要返回的是属性值,函数传参解释如下:
1.index参数为对象在这个集合中的索引值
2.class参数为这个对象原先的class属性值
实例:
<!DOCTYPE html> <html lang=\'zh-cn\'> <head> <title>Insert you title</title> <meta http-equiv=\'description\' content=\'this is my page\'> <meta http-equiv=\'keywords\' content=\'keyword1,keyword2,keyword3\'> <meta http-equiv="Content-Type" content="text/html; charset=utf-8"> <!-- <script type=\'text/javascript\' src=\'./js/jquery-3.0.0.js\'></script> --> <script type=\'text/javascript\' src=\'./js/jquery-1.12.1.min.js\'></script> <style type=\'text/css\'> input{font:400 13px/20px \'Courier New\';color:#000;} .addOne{padding:0 8px;} .addTwo{color:#999;} </style> <script type=\'text/javascript\'> $(function(){ $(\'#user\').addClass(\'addOne addTwo\'); }); </script> </head> <body> <input type=\'text\' id=\'user\' required="required" value=\'user\'/> </body> </html>