Allow only numeric value in a textbox on a form

Remove //** From the html codes:

This is the function in the header tag

function AllowNumeric(e) {
var iKeyCode = 0;
if (window.event)
iKeyCode = window.event.keyCode
else if (e)
iKeyCode = e.which;
if (iKeyCode > 47 && iKeyCode < 58)
return true
else
return false;

Here is the HTML for the textbox

//////(<)//**
INPUT onkeypress="javascript: return AllowNumeric(event);" id="txtAcctNo" style="WIDTH: 120px; HEIGHT: 20px"
type="text" maxLength="8" runat="server" size="14"
//**>///////