js相对定位

效果图:



<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge,chrome=1">
<title>Examples</title>
<meta name="description" content="">
<meta name="keywords" content="">
<link href="" rel="stylesheet">
<style>
</style>
</head>
<body>
	<div style="width:1200px;height:120px;background:red;"  id="div1">aaaaaaaaaaaaaaaa</div>
	<div style="width:1200px;height:120px;background:green;">aaaaaaaaaaaaaaaa</div>
	<div style="width:1200;height:120px;">aaaaaaaaaaaaaaaa</div>
	<div id="weixin_img">
		<img src="weixin.jpg" alt="" style="width:130px;">
	</div>
	<div style="width:1200px;height:1200px;background:green;">aaaaaaaaaaaaaaaa</div>
</body>
<script>

var div1=document.getElementById('div1');	
/*获取元素的纵坐标*/
function getTop(e)
{
   var offset=e.offsetTop;
   if(e.offsetParent!=null){
     offset+=getTop(e.offsetParent);
   }         
   return offset;
}
/*获取元素的横坐标*/
function getLeft(e)
{
   var offset=e.offsetLeft;
   if(e.offsetParent!=null){
      offset+=getLeft(e.offsetParent);
   } 
   return offset;
} 

document.getElementById('weixin_img').style.position="fixed";
document.getElementById('weixin_img').style.top=getTop(div1)+"px";
document.getElementById('weixin_img').style.left=(getLeft(div1)+1200)+"px";

</script>
</html>

js相对定位

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