function convertCurrency(currencyDigits) {
    // Constants:
            var MAXIMUM_NUMBER = 99999999999.99;
            // Predefine the radix characters and currency symbols for output:
            var CN_ZERO = "零";
            var CN_ONE = "壹";
            var CN_TWO = "贰";
            var CN_THREE = "叁";
            var CN_FOUR = "肆";
            var CN_FIVE = "伍";
            var CN_SIX = "陆";
            var CN_SEVEN = "柒";
            var CN_EIGHT = "捌";
            var CN_NINE = "玖";
            var CN_TEN = "拾";
            var CN_HUNDRED = "佰";
            var CN_THOUSAND = "仟";
            var CN_TEN_THOUSAND = "万";
            var CN_HUNDRED_MILLION = "亿";
            var CN_SYMBOL = "";
            var CN_DOLLAR = "元";
            var CN_TEN_CENT = "角";
            var CN_CENT = "分";
            var CN_INTEGER = "整";
    
    // Variables:
            var integral;    // Represent integral part of digit number.
            var decimal;    // Represent decimal part of digit number.
            var outputCharacters;    // The output result.
            var parts;
            var digits, radices, bigRadices, decimals;
            var zeroCount;
            var i, p, d;
            var quotient, modulus;
    
    // Validate input string:
            currencyDigits = currencyDigits.toString();
            if (currencyDigits == "") {
                alert("您的输入为空！");
                return "";
            }
            if (currencyDigits.match(/[^,.\d]/) != null) {
                alert("输入包含非法字符!");
                return "";
            }
            if ((currencyDigits).match(/^((\d{1,3}(,\d{3})*(.((\d{3},)*\d{1,3}))?)|(\d+(.\d+)?))$/) == null) {
                alert("输入有误!");
                return "";
            }
    
    // Normalize the format of input digits:
            currencyDigits = currencyDigits.replace(/,/g, "");    // Remove comma delimiters.
            currencyDigits = currencyDigits.replace(/^0+/, "");    // Trim zeros at the beginning.
            // Assert the number is not greater than the maximum number.
            if (Number(currencyDigits) > MAXIMUM_NUMBER) {
                alert("数额太大，转换金额上限小于1千亿!");
                return "";
            }
    
    // Process the coversion from currency digits to characters:
            // Separate integral and decimal parts before processing coversion:
            parts = currencyDigits.split(".");
            if (parts.length > 1) {
                integral = parts[0];
                decimal = parts[1];
                // Cut down redundant decimal digits that are after the second.
                decimal = decimal.substr(0, 2);
            }
            else {
                integral = parts[0];
                decimal = "";
            }
            // Prepare the characters corresponding to the digits:
            digits = new Array(CN_ZERO, CN_ONE, CN_TWO, CN_THREE, CN_FOUR, CN_FIVE, CN_SIX, CN_SEVEN, CN_EIGHT, CN_NINE);
            radices = new Array("", CN_TEN, CN_HUNDRED, CN_THOUSAND);
            bigRadices = new Array("", CN_TEN_THOUSAND, CN_HUNDRED_MILLION);
            decimals = new Array(CN_TEN_CENT, CN_CENT);
            // Start processing:
            outputCharacters = "";
            // Process integral part if it is larger than 0:
            if (Number(integral) > 0) {
                zeroCount = 0;
                for (i = 0; i < integral.length; i++) {
                    p = integral.length - i - 1;
                    d = integral.substr(i, 1);
                    quotient = p / 4;
                    modulus = p % 4;
                    if (d == "0") {
                        zeroCount++;
                    }
                    else {
                        if (zeroCount > 0)
                        {
                            outputCharacters += digits[0];
                        }
                        zeroCount = 0;
                        outputCharacters += digits[Number(d)] + radices[modulus];
                    }
                    if (modulus == 0 && zeroCount < 4) {
                        outputCharacters += bigRadices[quotient];
                    }
                }
                outputCharacters += CN_DOLLAR;
            }
            // Process decimal part if there is:
            if (decimal != "") {
                for (i = 0; i < decimal.length; i++) {
                    d = decimal.substr(i, 1);
                    if (d != "0") {
                        outputCharacters += digits[Number(d)] + decimals[i];
                    }
                }
            }
            // Confirm and return the final output string:
            if (outputCharacters == "") {
                outputCharacters = CN_ZERO + CN_DOLLAR;
            }
            if (decimal == "") {
                outputCharacters += CN_INTEGER;
            }
            outputCharacters = CN_SYMBOL + outputCharacters;
            return outputCharacters;
        }