首先获得网页元素的绝对位置后在相应的位置创建一个遮挡层，可实现一个水印样式。该例可用于为图片加版权，或隐藏图片的下载地址等。缺点是改变浏览器大小时有页面有闪烁。
<html><head><meta http-equiv="Content-Type" content="text/html; charset=gb2312"><title>无标题文档</title><script> //取得元素（图像）的绝对位置 function getDim(el) { for (var lx=0,ly=0; el!=null; lx+=el.offsetLeft,ly+=el.offsetTop,el=el.offsetParent); return {x:lx,y:ly} } //创建遮挡层 function createLayer(el) { myImgDim = getDim(el); document.writeln("<div id='Layer1' style='position:absolute; z-index:1; left: "+myImgDim.x+"px; top: "+myImgDim.y+"px;'>"); document.writeln("<img src=logo.gif width=38 height=17>"); document.writeln("</div>"); } //浏览器窗口大小改变时刷新页面 window.οnresize=function() { location.reload(); }</script><link href="j.css" rel="stylesheet" type="text/css"></head>
<body><br><br><table width="407" height="268" align="center"> <tr> <td align="center"><span id=MySpan><img src="image/logo1.gif" width="150" height="78" id=MyImage></span><span id=MySpan><img src="image/logo1.gif" width="150" height="78" id=MyImage2></span></td> </tr></table>
<span id=MySpan><img src="image/logo1.gif" width="150" height="78" id=MyImage3></span><br><span id=MySpan><img src="image/logo1.gif" width="150" height="78" id=MyImage4></span><script> createLayer(document.images.MyImage); createLayer(document.images.MyImage2); createLayer(document.images.MyImage3); createLayer(document.images.MyImage4);</script></body></html>
