смотря какой браузер
<!DOCTYPE HTML>
<html>
<head>
<title>Untitled</title>
<meta charset="utf-8">
<style type="text/css">
#test{
background-color: #FF0000;
height: 50px;
width: 50px;
position: relative;
top: 150px;
}
body{
height: 5000px;
}
</style>
<script>
window.onscroll = function() {
var s = document.documentElement.scrollTop||document.body.scrollTop,
e = document.getElementById('test').style;
if(!this.scrollFlag && s > 100) {
this.scrollFlag = true;
e.display = 'none';
}
else if(this.scrollFlag && s < 100) {
this.scrollFlag = false;
e.display = 'block';
}
}
</script>
</head>
<body>
<div id="test"></div>
</body>
</html>
|