<!doctype html public "-//w3c//dtd xhtml 1.0 transitional//en" "http://www.w3.org/tr/xhtml1/dtd/xhtml1-transitional.dtd">
<html xmlns="http://www.111cn.net/1999/xhtml">
<head>
<meta http-equiv="content-type" content="text/html; charset=gb2312" />
<title>js验证数字</title>
</head><body>
<form id="form1" name="form1" method="post" onsubmit="网页特效:return check();" >
<table width="98%" border="0" class="table_list">
<tr>
<td width="51%">
<input type="text" name="num" id="num" />
<input type="submit" name="button" id="button" value="验证数字" /></td>
<td width="33%"> </td>
</tr>
</table>
</form><script language="javascript">
function check()
{
var num = document.getelementbyid('num').value;
if( isnan(num) || num == "" )
{
alert('请输入一个数字');
document.getelementbyid('num').focus();
return false;
}
}</script>
</body>
</html>