Format a number with commas (commify) as the thousands separator.
/**
* Print a number with commas as the thousands separator.
*
* @example 1000 => "1,000"
* @param {number} x The numnber to print
* @return {string} The number with commas as the thousands separator
*
* @link https://stackoverflow.com/a/2901298
*/
function numberWithCommas(x) {
return x.toString().replace(/\B(?=(\d{3})+(?!\d))/g, ',');
}