在网上转悠的时候，看到了一篇不错的效果，便转载过来，以免以后用的时候难得找。
主要是运用"position:fixed;"属性。
直接上代码:
<!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>lock page</title>
<meta name="author" content="www.planeart.cn" />
<style>
#pageOverlay { position:fixed; top:0; left:0; z-index:1987; width:100%; height:100%; background:#000; filter:alpha(opacity=70); opacity:0.7; }
ul li{ height:300px;}
#color1{background:#6cf;}
#color2{background:#09c;}
#color3{background:#9ff;}
</style>
</head>
<body>
<ul id="test" onclick="document.getElementById('pageOverlay').style.visibility = 'visible'">
<li id="color1"></li>
<li id="color2"></li>
<li id="color3"></li>
</ul>
<div id="pageOverlay" onclick="this.style.visibility = 'hidden'"></div>
</body>
</html>
可惜ie6并不支持"position:fixed;"属性，那么只有使用JS动态修改top值模拟静止定位，拖动滚动条的时候遮罩层肯定会抖动，因为每改变一次ie都会重新渲染一次。但是微软却给我们提供了一个非常有趣的特性，如果给html或者body标签设置一个静止定位的背景图片，层在拖动滚动条的时候就不会抖动了，几乎完美的模拟了“position:fixed”。
上代码：
<!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>lock page</title>
<meta name="author" content="www.planeart.cn" />
<style>
#pageOverlay { position:fixed; top:0; left:0; z-index:1987; width:100%; height:100%; background:#000; filter:alpha(opacity=70); opacity:0.7; }
/*IE6 fixed*/
* html { background:url(*) fixed; }
* html body { margin:0; height:100%; }
* html #pageOverlay { position: absolute; left: expression(documentElement.scrollLeft + documentElement.clientWidth - this.offsetWidth); top: expression(documentElement.scrollTop + documentElement.clientHeight - this.offsetHeight); }
ul li{height:300px;}
#color1{background:#6cf;}
#color2{background:#09c;}
#color3{background:#9ff;}
</style>
</head>
<body>
<ul id="test" onclick="document.getElementById('pageOverlay').style.visibility = 'visible'">
<li id="color1"></li>
<li id="color2"></li>
<li id="color3"></li>
</ul>
<div id="pageOverlay" onclick="this.style.visibility = 'hidden'"></div>
</body>
</html>
现在在ie6及其他浏览器都能实现锁屏了，接着咱们就再添加一点脚本，让锁屏的时候后可以中断用户操作，把滚动条、滚轮、tab键、全选、刷新、右键统统禁止掉，模拟真正的‘锁屏’。
上代码：
<!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>lock page</title>
<meta name="author" content="www.planeart.cn" />
<style>
#pageOverlay { visibility:hidden; position:fixed; top:0; left:0; z-index:1987; width:100%; height:100%; background:#000; filter:alpha(opacity=70); opacity:0.7; }
/*IE6 fixed*/
* html { background:url(*) fixed; }
* html body { margin:0; height:100%; }
* html #pageOverlay { position: absolute; left: expression(documentElement.scrollLeft + documentElement.clientWidth - this.offsetWidth); top: expression(documentElement.scrollTop + documentElement.clientHeight - this.offsetHeight); }
*{margin:0;padding:0;}
ul{list-style:none;}
ul li{height:300px;}
#color1{background:#6cf;}
#color2{background:#09c;}
#color3{background:#9ff;}
</style>
<script>
(function(){
// 获取对象
var $ = function (id){
return document.getElementById(id);
};
// 遍历
var each = function(a, b) {
for (var i = 0, len = a.length; i < len; i++) b(a[i], i); }; // 事件绑定 var bind = function (obj, type, fn) { if (obj.attachEvent) { obj['e' + type + fn] = fn; obj[type + fn] = function(){obj['e' + type + fn](window.event);} obj.attachEvent('on' + type, obj[type + fn]); } else { obj.addEventListener(type, fn, false); }; }; // 移除事件 var unbind = function (obj, type, fn) { if (obj.detachEvent) { try { obj.detachEvent('on' + type, obj[type + fn]); obj[type + fn] = null; } catch(_) {}; } else { obj.removeEventListener(type, fn, false); }; }; // 阻止浏览器默认行为 var stopDefault = function(e){ e.preventDefault ? e.preventDefault() : e.returnValue = false; }; // 获取页面滚动条位置 var getPage = function(){ var dd = document.documentElement, db = document.body; return { left: Math.max(dd.scrollLeft, db.scrollLeft), top: Math.max(dd.scrollTop, db.scrollTop) }; }; // 锁屏 var lock = { show: function(){ $('pageOverlay').style.visibility = 'visible'; var p = getPage(), left = p.left, top = p.top; // 页面鼠标操作限制this.mouse = function(evt){ var e = evt || window.event; stopDefault(e); scroll(left, top); }; each(['DOMMouseScroll', 'mousewheel', 'scroll', 'contextmenu'], function(o, i) { bind(document, o, lock.mouse); }); // 屏蔽特定按键: F5, Ctrl + R, Ctrl + A, Tab, Up, Downthis.key = function(evt){ var e = evt || window.event, key = e.keyCode; if((key == 116) || (e.ctrlKey && key == 82) || (e.ctrlKey && key == 65) || (key == 9) || (key == 38) || (key == 40)) { try{ e.keyCode = 0; }catch(_){}; stopDefault(e); }; }; bind(document, 'keydown', lock.key); }, close: function(){ $('pageOverlay').style.visibility = 'hidden'; each(['DOMMouseScroll', 'mousewheel', 'scroll', 'contextmenu'], function(o, i) { unbind(document, o, lock.mouse); }); unbind(document, 'keydown', lock.key); } }; bind(window, 'load', function(){ $('btn_lock').onclick = function(){ lock.show(); }; $('pageOverlay').onclick = function(){ lock.close(); }; });})();</script></head><body><button id="btn_lock" style="position: absolute; left:50%; top:40%; ">开启锁屏</button><ul id="test"><li id="color1"></li><li id="color2"></li><li id="color3"></li></ul><div id="pageOverlay"></div></body></html>