Quick Currency formatter

quickcurrency.js

/* JavaScript: US currency helper functions
-------------------------------------------------------*/

/**
* Formats any number, string or HTML string to a number with two trailing decimals
* @param {String} html  Any number, string or HTML string
* @return {Number}  Returns a number with two trailing decimals
*/
var toCurrency = function(html) {
  var currency = html.match(/[\d\.]+/g);
      currency = currency.join('');
  return parseFloat(currency).toFixed(2);
}
// toCurrency('<span class="sign">$</span><span class="dollar">50</span><span class="decimal">.</span><span class="cents">00</span>');
// toCurrency('50');
// returns number 50.00

/**
* Formats any number to a predifined HTML string
* @param {Number} num  Any number
* @return {String}  Returns an HTML string with spans and classes for sign, dollar, decimal, cents
*/
var currencyToHTML = function(num) {
  num = num.toString();
  num = num.split('.');
  var dollar = num[0];
  var cents  = (num[1] === undefined) ? '00' : num[1];
  var format = '<span class="sign">$</span>';
      format += '<span class="dollar">' + dollar + '</span>';
      format += '<span class="decimal">.</span>';
      format += '<span class="cents">' + cents + '</span>';
  return format;
}
// currencyToHTML('50.00');
// returns string'<span class="sign">$</span><span class="dollar">50</span><span class="decimal">.</span><span class="cents">00</span>')

/**
* Adds two Numbers and returns formatted value
* @param {Number} num1  Initial number
* @param {Number} num2  Number to be added
* @return {String}  Returns a value with two trailing decimals
*/
var sumCurrency = function(num1, num2) {
  num1 = isNaN(num1) || num1 === '' || num1 === null ? 0.00 : num1;
  num2 = isNaN(num2) || num2 === '' || num2 === null ? 0.00 : num2;
  var total = num1 + num2;
  return parseFloat(total).toFixed(2);
}
// sumCurrency('50','9.99');
// returns number 59.99

/**
* Substracs two Numbers and returns formatted value
* @param {Number} num1  Initial number
* @param {Number} num2  Number to be subracted
* @return {String}  Returns a value with two trailing decimals
*/
var subCurrency = function(num1, num2) {
  num1 = isNaN(num1) || num1 === '' || num1 === null ? 0.00 : num1;
  num2 = isNaN(num2) || num2 === '' || num2 === null ? 0.00 : num2;
  var total = num1 - num2;
  return parseFloat(total).toFixed(2);
}
// subCurrency('50','9.99');
// returns number 50.01