jquery学习 (3)文本框获取焦点之后变换样式

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<html xmlns="http://www.w3.org/1999/xhtml">

<head>

<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />

<title></title>

<style type="text/css">





body{

    font:normal 12px/17px Arial;

}

div{

    padding:2px;

} 

input, textarea { 

     width: 12em; 

     border: 1px solid #888;

}

.focus { 

     border: 1px solid #f00;

     background: #fcc;

} 



</style>

<!--   引入jQuery -->

<script src="../../scripts/jquery.js" type="text/javascript"></script>

<script type="text/javascript">

    $(function(){

        $(":input").focus(function(){

              $(this).addClass("focus");

              if($(this).val() ==this.defaultValue){  

                  $(this).val("");     //获取焦点之后判断是不是更改值      

              } 

        }).blur(function(){

             $(this).removeClass("focus");

             if ($(this).val() == '') {

                $(this).val(this.defaultValue);

             }

        });

    })

    </script>

        

</head>

<body>

    <form action="" method="post" id="regForm">

        <fieldset>

            <legend>个人基本信息</legend>

                <div>

                    <label  for="username">名称:</label>

                    <input id="username" type="text" value="名称" />

                </div>

                <div>

                    <label for="pass">密码:</label>

                    <input id="pass" type="password" value="密码" />

                </div>

                <div>

                    <label for="msg">详细信息:</label>

                    <textarea id="msg" rows="2" cols="20">详细信息</textarea>

                </div>

        </fieldset>

    </form>

</body>

</html>

 

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