Javascript Example
Screen shot
Javascript code to validate Numeric value.

<html>
<head>
<title>Javascript Mobile Number Validation</title>
<script language="javascript">
function validate()
{
if(isNaN(document.frm.mobile.value))
{
alert("Mobile Number should be numeric");
document.frm.mobile.focus();
return false;
}
return true;
}
</script>
</head>
<body>
<form name="frm" action="" method="post" onSubmit="return validate()">
<table border="1" align="center">
<tr>
<td>Mobile Number</td>
<td><input name="mobile" type="text"></td>
</tr>
<td colspan="2">
<input name="btnsubmit" type="submit" value="Submit">
</td>
</tr>
</table>
</form>
</body>
</html>

You can download source code here