<form name="frmtest"> <input type="text" name="txt1"> <input type="button" value="check" onclick="checkInput()"> </form> <script language="javascript"> function checkInput() { if (!isNaN(document.frmtest.txt1.value)) alert("it is a number"); else alert("it is not a number"); } </script>
<input type="text" name="txt1">
<input type="button" value="check" onclick="checkInput()">
</form>
<script language="javascript">
function checkInput()
{
if (!isNaN(document.frmtest.txt1.value))
alert("it is a number");
else
alert("it is not a number");
}
</script>