function format (num) {
return (num.toFixed(2) + '').replace(/\d{1,3}(?=(\d{3})+(\.\d*)?$)/g, '$&,');
}
var num = 12;
console.log(format(num));
function format (num) {
return (num.toFixed(2) + '').replace(/\d{1,3}(?=(\d{3})+(\.\d*)?$)/g, '$&,');
}
var num = 12;
console.log(format(num));