Js千位分隔符

//JS实现千位分隔符
        function formatNumber(nbr) {
            if (nbr && nbr > 1000) {
                //1. 从后往前插进数组，然后 join(",");
                var newNbr = nbr.toString();
                var arr = [];
                while (newNbr > 1000) {
                    var idx = newNbr.indexOf(".");
                    if (idx > -1) { //包含小数
                        arr.push(newNbr.substr(idx - 3, newNbr.length - (idx - 3)));
                        newNbr = newNbr.substr(0, idx - 3);
                    }
                    else {
                        arr.push(newNbr.substr(newNbr.length - 3, 3));
                        newNbr = newNbr.substr(0, newNbr.length - 3);
                    }
                }
                arr.push(newNbr);
                arr.reverse();
                return arr.join(",");
            }
            else {
                return nbr;
            }
        }
       
        //JS使用正则实现千位分割符
        function commafy(num) {
            num = num + "";
            var re = /(-?d+)(d{3})/;
            while (re.test(num)) {
                num = num.replace(re, "$1,$2");
            }
            return num;
        }