class NumberUtil {

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

	static numberOfDigits(number) {
		return Math.floor(Math.log(number) / Math.LN10 + 1);	// bug : 1000 -> expected 4 but 3
	}

}