Adding comma as thousands separator (javascript) - output being deleted instead

Question

I am attempting to dynamically adjust a numerical value entered to include thousand separators

Here is my code:

function addCommas(nStr) {
    nStr +         


        

Answer 1

Try this regex:

function numberWithCommas(x) {
  return x.toString().replace(/\B(?=(\d{3})+(?!\d))/g, ",");
}