<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<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>
<script type="text/javascript">
function jj(){
var a=document.getElementById("aa").value;
var reg=/^\d{0,7}(\.\d{0,2})?$/g;
if(!reg.test(a)){
alert("错误信息");
}else{
alert("正确");
}
}
</script>
</head>
<body>
<input type="text" id="aa"/>
<input type="button" value="提交" onclick="jj();"/>
</body>
</html>
原文：http://www.cnblogs.com/lanliying/p/4892480.html