add commas to currency

gistfile1.js

  currency_comma = function (str) {
		str += '';

		var arr = str.split('.'),
			integer = arr[0],
			fraction = arr.length > 1 ? '.' + arr[1] : '';

		var regex = /(\d+)(\d{3})/;
		while (regex.test(integer)) {
			integer = integer.replace(regex, '$1' + ',' + '$2');
		}
		return integer + fraction;
	}