<!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>无标题文档</title>
<style>
*{margin:0;padding:0;}
#login{width:300px;height:300px;border:1px solid black;position:relative;}
#close{position:absolute;top:0;right:0;}
</style>
<script type="text/javascript" src="jquery-1.10.1.min.js"></script>
<script>
$(function(){
$('#input1').click(function(){
var oLogin = $('<div id="login"><p>用户名:<input type="text" value="" id="input2"/></p><p>密码:<input type="text" value="" id="input2"/></p><span id="close">x</span></div>'); //juery 创建元素<> 注意不要留有空格
$('body').append(oLogin);
oLogin.css('left',($(window).width() - oLogin.outerWidth())/2);
oLogin.css('top',($(window).height() - oLogin.outerHeight())/2);
$('#close').click(function(){
oLogin.remove();
});
$(window).on('resize scroll',function(){
oLogin.css('left',($(window).width() - oLogin.outerWidth())/2);
oLogin.css('top',($(window).height() - oLogin.outerHeight())/2+$(window).scrollTop());
});
});
});
</script>
</head>
<body style="height:2000px;">
<input type="button" value="点击" id="input1"/>
</body>
</html>