Javascript number formats.

function FormatNumber(num,decimalNum,bolLeadingZero,bolParens,bolCommas)
/**********************************************************************
	IN:
		NUM - the number to format
		decimalNum - the number of decimal places to format the number to
		bolLeadingZero - true / false - display a leading zero for
										numbers between -1 and 1
		bolParens - true / false - use parenthesis around negative numbers
		bolCommas - put commas as number separators.
 
	RETVAL:
		The formatted number!
 **********************************************************************/
{ 
        if (isNaN(parseInt(num))) return "NaN";

	var tmpNum = num;
	var iSign = num < 0 ? -1 : 1;		// Get sign of number
	
	// Adjust number so only the specified number of numbers after
	// the decimal point are shown.
	tmpNum *= Math.pow(10,decimalNum);
	tmpNum = Math.round(Math.abs(tmpNum))
	tmpNum /= Math.pow(10,decimalNum);
	tmpNum *= iSign;					// Readjust for sign
	
	
	// Create a string object to do our formatting on
	var tmpNumStr = new String(tmpNum);

	// See if we need to strip out the leading zero or not.
	if (!bolLeadingZero && num < 1 && num > -1 && num != 0)
		if (num > 0)
			tmpNumStr = tmpNumStr.substring(1,tmpNumStr.length);
		else
			tmpNumStr = "-" + tmpNumStr.substring(2,tmpNumStr.length);
		
	// See if we need to put in the commas
	if (bolCommas && (num >= 1000 || num <= -1000)) {
		var iStart = tmpNumStr.indexOf(".");
		if (iStart < 0)
			iStart = tmpNumStr.length;

		iStart -= 3;
		while (iStart >= 1) {
			tmpNumStr = tmpNumStr.substring(0,iStart) + "," + tmpNumStr.substring(iStart,tmpNumStr.length)
			iStart -= 3;
		}		
	}

	// See if we need to use parenthesis
	if (bolParens && num < 0)
		tmpNumStr = "(" + tmpNumStr.substring(1,tmpNumStr.length) + ")";

	return tmpNumStr;		// Return our formatted string!
}

See also:

• https://www.w3schools.com/js/js_number_methods.asp +