<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>demo</title>
<style>
body[zoom='scale']:before{
content: '您的网页处于缩放状态，请按 Ctrl+0 恢复到浏览器默认大小';
z-index: 9999;
position: fixed;
left:0;
top:0;
width: 100%;
line-height: 44px;
background: rgba(50,57,65,0.9);
border-bottom: 1px solid #ccc;
text-align: center;
font-family: 黑体;
color: #fff;
}
</style>
</head>
<body>
<script src="http://cdn.bootcss.com/jquery/2.1.4/jquery.min.js"></script>
<script src="http://www.papastyle.cn/detectZoom/jquery.detectZoom.js"></script>
<div>js监听页面放大缩小</div>
</body>
</html>