<script type="text/javascript"> function handleMouseMove(e){ var evt =e||event; var srcEl =evt.target||evt.srcElement; var rect =srcEl.getBoundingClientRect();
var width =srcEl.offsetWidth; var xPos =evt.clientX; var isInLeft=Math.round((xPos-rect.left)/width)==0;
<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>
</head>
<body>
<p><img src="http://www.google.com.hk/intl/zh-CN/images/logo_cn.png"
onmousemove="handleMouseMove(event)"
/>
<script type="text/javascript">
function handleMouseMove(e){
var evt =e||event;
var srcEl =evt.target||evt.srcElement;
var rect =srcEl.getBoundingClientRect();
var width =srcEl.offsetWidth;
var xPos =evt.clientX;
var isInLeft=Math.round((xPos-rect.left)/width)==0;
if(isInLeft){
srcEl.style.cursor="wait";
}else{
srcEl.style.cursor="help";
}
}
</script>
<br/>
</p>
<p> </p>
<p> </p>
<p> </p>
<p> </p>
<p> </p>
<p> </p>
<p> </p>
<p> </p>
<p> </p>
<p> </p>
<p> </p>
<p> </p>
<p> </p>
<p> </p>
<p> </p>
<p> </p>
<p> </p>
<p> </p>
<p> </p>
<p> </p>
<p> </p>
<p> </p>
<p> </p>
<p> </p>
<p> </p>
<p> </p>
<p> </p>
</body>
</html>
var isInLeft=Math.round((xPos-rect.left)/width)==0;
这种写法的,逻辑能给我说明一下吗?