function thousandBitSeparator(num) {
num=num.toFixed(2);
return num && num
.toString()
.replace(/(\d)(?=(\d{3})+\.)/g, function($1,$2) {
return $2 + ",";
});
}
console.log(thousandBitSeparator(-111111111111110.0000001));
原文：http://www.cnblogs.com/taiyanghua0522/p/7162229.html