js验证符合用户体验的网页表单特效

<meta http-equiv="content-type" content="text/html; charset=utf-8"> <title>js+css实现的一种交互体验</title> <style> @charset "utf-8"; /*元素初始值*/ html {background: #fff;} body,div,dl,dt,dd,ul,ol,li,h1,h2,h3,h4,h5,h6,pre,form,fieldset,input,p,blockquote,th,td,ins,hr{margin: 0px;padding: 0px;} p{cursor: text;} h1,h2,h3,h4,h5,h6{font-size:100%;} ol,ul{list-style-type: none;} address,caption,cite,code,dfn,em,th,var{font-style:normal;font-weight:normal;} table{border-collapse:collapse;} fieldset,img{border:0;} img{display:block;} caption,th{text-align:left;} body{position: relative;font-size:62.5%;font-family: "宋体"} a{text-decoration: none;} /*demo所用元素值*/ #need {margin: 20px auto 0;width: 610px;} #need li {height: 26px;width: 600px;font: 12px/26px arial, helvetica, sans-serif;background: #ffd;border-bottom: 1px dashed #e0e0e0;display: block;cursor: text;padding: 7px 0px 7px 10px!important;padding: 5px 0px 5px 10px;} #need li:hover,#need li.hover {background: #ffe8e8;} #need input {line-height: 14px;background: #fff;height: 14px;width: 200px;border: 1px solid #e0e0e0;vertical-align: middle;padding: 6px;} #need label {padding-left: 30px;} #need label.old_password {background-position: 0 -277px;} #need label.new_password {background-position: 0 -1576px;} #need label.repassword {background-position: 0 -1638px;} #need label.email {background-position: 0 -429px;} #need dfn {display: none;} #need li:hover dfn, #need li.hover dfn {display:inline;margin-left: 7px;color: #676767;} </style> <ol id="need"> <li> <label class="old_password">原始密码：</label> <input name="" type="password" id=""> </li> <li> <label class="new_password">新的密码：</label> <input name="" type="password" id=""><dfn>（密码长度为6~20字节。不想修改请留空）</dfn> </li> <li> <label class="repassword">重复密码：</label> <input name="" type="password" id=""> </li> <li> <label class="email">邮箱设置：</label> <input name="" type="text" id=""><dfn>（codemoz! 承诺绝不会给您发送任何垃圾邮件。）</dfn> </li> </ol>
[ctrl+a 全选 注:如需引入外部js需刷新才能执行]