<!doctype html>
<head>
<meta charset=utf-8" />
<title>javascript控制图片缩小或者放大</title>
</head>
<body>
<script type="text/javascript">
var oTime;
function changeSize(id,action){
var obj=document.getElementById(id);
obj.style.zoom=parseInt(obj.style.zoom)+(action==‘+‘?+10:-10)+‘%‘;
oTime=window.setTimeout(‘changeSize(\‘‘+id+‘\‘,\‘‘+action+‘\‘)‘,100);
}
document.onmouseup=function(){
window.clearTimeout(oTime);
}
</script>
<div style="height: 200px; overflow: auto;">
<img id="headImg" src="http://www.phpernote.com/images/logo.gif" width="67" height="55" style="zoom: 100%;"></div>
<button onmousedown="changeSize(‘headImg‘,‘+‘);" onmouseup="window.clearTimeout(oTime);">放大</button>
<button onmousedown="changeSize(‘headImg‘,‘-‘);" onmouseup="window.clearTimeout(oTime);">缩小</button>
</body>
</html>
原文：http://www.cnblogs.com/a-mumu/p/4739930.html