How to Convert text of adjacent numbers to displayed as text of number's thousands comma separated?

Question

Question: I have 12345678 as text how to get 12,345,678? And as many more numbers between single quote?

I tried this code, but it's qualified for 123456.length <= 6 :-

 if (int.length > 3) {
   int = int.substr(0, int.length - 3) + "," + int.substr(int.length - 3, 3);
}

Answer 1

function comma(num) {
  var newNum;
  var len = num.length;
  if (len > 3) {
    var comNo = len % 3;
    newNum = num
      .split("")
      .reverse()
      .join("")
      .match(/.{1,3}/g)
      .map(function(current) {
        return current
          .split("")
          .reverse()
          .join("");
      });

    newNum.reverse();

    return newNum.join();
  } else {
    return num;
  }
}
int = comma(int);