首先是动态修改数据框的值：
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html> <head> <title>XXX</title> <meta http-equiv="content-type" content="text/html; charset=UTF-8"> <script language="JavaScript" src="../js/jquery-1.4.2.js"></script> <style type="text/css"> div,span{ width: 140px; height: 140px; margin: 20px; background: #9999CC; border: #000 1px solid; float:left; font-size: 17px; font-family:Roman; } div.mini{ width: 30px; height: 30px; background: #CC66FF; border: #000 1px solid; font-size: 12px; font-family:Roman; } </style> <!--引入jquery的js库--> </head> <body> <input type="text" value="用户邮箱/手机号/用户名" id="b1"/><br> <input type="password" value="" id="b2"/><br> <input type="button" value="登陆" id="b3"/> <br> </body> <script language="JavaScript"> $("#b1").focus(function(){ if($(this).val()==this.defaultValue){ $(this).val(""); } }); $("#b1").blur(function(){ if($(this).val()==""){ $(this).val(this.defaultValue); } }); </script> </html>再来是是动态修改placeholder的值：
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html> <head> <title>XXX</title> <meta http-equiv="content-type" content="text/html; charset=UTF-8"> <script language="JavaScript" src="../js/jquery-1.4.2.js"></script> <style type="text/css"> div,span{ width: 140px; height: 140px; margin: 20px; background: #9999CC; border: #000 1px solid; float:left; font-size: 17px; font-family:Roman; } div.mini{ width: 30px; height: 30px; background: #CC66FF; border: #000 1px solid; font-size: 12px; font-family:Roman; } </style> <!--引入jquery的js库--> </head> <body> <input type="text" placeholder="用户邮箱/手机号/用户名" id="b1"/><br> <input type="password" value="" id="b2"/><br> <input type="button" value="登陆" id="b3"/> <br> </body> <script language="JavaScript"> $("#b1").focus(function(){ $(this).attr('placeholder',""); }); $("#b1").blur(function(){ if($(this).val()==""){ $(this).attr('placeholder','${sessionScope.xxxxxxx}'); } }); </script> </html>