1const formatToCurrency = amount => {
2  return "$" + amount.toFixed(2).replace(/\d(?=(\d{3})+\.)/g, "$&,");
3};
4formatToCurrency(12.34546); //"$12.35"
5formatToCurrency(42345255.356); //"$42,345,255.36

1(12345.67).toFixed(2).replace(/\d(?=(\d{3})+\.)/g, '$&,');  // 12,345.67

1// Create our number formatter.
2var formatter = new Intl.NumberFormat('en-US', {
3  style: 'currency',
4  currency: 'USD',
5});
6
7formatter.format(2500); /* $2,500.00 */

1function numberWithCommas(x) {
2    return x.toString().replace(/\B(?=(\d{3})+(?!\d))/g, ",");
3}
4

1var value = 2.9802453587962963;
2var wholeNum = Math.floor(value);
3console.log(wholeNum);  // output ==> 2

1var x = parseFloat('9.656');
2
3x.toFixed(0);           // returns 10
4x.toFixed(2);           // returns 9.66
5x.toFixed(4);           // returns 9.6560
6x.toFixed(6);