1var n = 34523453.345
2n.toLocaleString()
3"34,523,453.345"
4

1function formatMoney(n) {
2    return "$ " + (Math.round(n * 100) / 100).toLocaleString();
3}
4
5n = 2123000;
6// =>2,123,000

1//ES6 Way
2const numberWithCommas = (x) => {
3  return x.toString().replace(/\B(?=(\d{3})+(?!\d))/g, ',');
4}

1foramtNumber = (num,div=",")=>{
2  return num.toString().replace(/\B(?=(\d{3})+(?!\d))/g, div);
3
4}

1x.toString().toLocaleString(); // x must be a number