jquery.tocurrency.js

// jQuery plugin:
// converts a float number as text in some element
// into US currency
//
// Ex: 
// <span id="price">1234988.3400</span>
//
// $('span#price').toCurrency()
// => <span id="price">$1,234,988.34</span>
(function($) {
  $.fn.toCurrency = function() {
    return this.each(function() {
      var currency = Math.abs($(this).text()).toFixed(2),
          dollars = currency.split('.')[0],
          cents = currency.split('.')[1]
      
      for (var i = 0; i < Math.floor((dollars.length - (1 + i)) / 3); i++)
        dollars = dollars.substring(0, dollars.length - (4 * i + 3)) + ',' +
         dollars.substring(dollars.length - (4 * i + 3))
    
      $(this).text('$' + dollars + '.' + cents)
    }
  }
})(jQuery);