Format Currency With Javascript

</script>
function formatCurrency(num) {
     num = num.toString().replace(/\Rp|/g,'');
     if(isNaN(num))
         num = "\";
     sign = (num == (num = Math.abs(num)));
     num = Math.floor(num*100+0.50000000001);
     cents = num%100;
     num = Math.floor(num/100).toString();
     if(cents<10)
         cents = "0" + cents;
     for (var i = 0; i < Math.floor((num.length-(1+i))/3); i++)
         num = num.substring(0,num.length-(4*i+3))+'.'+
         num.substring(num.length-(4*i+3));
     return (((sign)?'':'-') + 'Rp ' + num + ',' + cents);

 }

document.write(formatCurrency(99021990));
</script>