format number javascript with comma

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

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

1formatedNumber = new Intl.NumberFormat().format(2561556862056.12)
2console.log(formatedNumber) // "2,561,556,862,056.12"

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

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