将人民币数字转换成大写形式

用JavaScript编写了一功能函数，完成如下功能：
1、对一给定字符串，如：1234.55，转换成正确的中文货币描述：如：人民币壹仟贰佰叁拾四元五角五分
2、输入的字符串形式可以是以下几种：带分隔符的，如：123,456,789.00；不带分隔符的，如：123456789
3、输出的中文货币描述要符合规范，如：0.3----人民币三角；0.33----人民币三角三分；1----人民币壹元整
100----人民币壹佰元整；1001----人民币壹仟零壹元整；10000001----人民币壹仟万零壹元整；
1001001----人民币壹仟零壹万零壹元整，等
4、最大转换能到百亿

具体的代码如下：

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<html>
<head>
  <title></title>
  <script language="jscript">
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 = "人民币";
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("Empty input!");
  return "";
}
if (currencyDigits.match(/[^,.\d]/) != null) {
  alert("Invalid characters in the input string!");
  return "";
}
if ((currencyDigits).match(/^((\d{1,3}(,\d{3})*(.((\d{3},)*\d{1,3}))?)|(\d+(.\d+)?))$/) == null) {
  alert("Illegal format of digit number!");
  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("Too large a number to convert!");
  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;
}
  </script>
</head>
<body>
  <INPUT id="Digits" type="text" name="Digits" size=20>
  <INPUT id="Convert" type="button" value="Convert" name="Convert" onclick="Result.value = convertCurrency(Digits.value);">
  <INPUT id="Result" type="text" name="Result" size=60>
</body>
</html>