可能的值
left ：在左侧不允许浮动元素
right ：在右侧不允许浮动元素
both ：在左右两侧均不允许浮动元素
none：默认。允许浮动元素出现在两侧。
实例
<html>
<head>
<style type="text/css">
img
{float:left;}
</style>
<script type="text/javascript">
function clearLeft()
{
document.getElementById("p1").style.clear="left";
}
</script>
</head>
<body>
<p id="p1">This is some text. This is some text. This is some text.
This is some text. This is some text. This is some text.
This is some text. This is some text. This is some text.</p>
<input type="button" onclick="clearLeft()"
value="Clear left side of text" />
</body>
</html>
