<html>
<script type="text/javascript">
<!--
function numberFormat(num){
return String(num).replace(/(-?\d*)(?!\d)/,
function(intPart){
return intPart.replace(/(\d)(?=(\d{3})+(?!\d))/g,"$1,");
});
}
//-->
</script>
<body>
<input type="button" value="click" onclick="alert(numberFormat(-10000000.000001))">
</body>
</html>
