(function($) {
  $.fn.countTo = function(options) {
    options = options || {};

    return $(this).each(function() {
      // set options for current element
      var settings = $.extend( 
        {},
        $.fn.countTo.defaults,
        { 
          from: $(this).data("from"),
          to: $(this).data("to"),
          speed: $(this).data("speed"),
          refreshInterval: $(this).data("refresh-interval"),
          decimals: $(this).data("decimals")
        },
        options
      );

      // how many times to update the value, and how much to increment the value on each update
      var loops = Math.ceil(settings.speed / settings.refreshInterval),
        increment = (settings.to - settings.from) / loops;

      // references & variables that will change with each update
      var self = this,
        $self = $(this),
        loopCount = 0,
        value = settings.from,
        data = $self.data("countTo") || {};

      $self.data("countTo", data);

      // if an existing interval can be found, clear it first
      if (data.interval) {
        clearInterval(data.interval);
      }
      data.interval = setInterval(updateTimer, settings.refreshInterval);

      // initialize the element with the starting value
      render(value);

      function updateTimer() {
        value += increment;
        loopCount++;

        render(value);

        if (typeof settings.onUpdate == "function") {
          settings.onUpdate.call(self, value);
        }

        if (loopCount >= loops) {
          // remove the interval
          $self.removeData("countTo");
          clearInterval(data.interval);
          value = settings.to;

          if (typeof settings.onComplete == "function") {
            settings.onComplete.call(self, value);
          }
        }
      }

      function render(value) {
        var formattedValue = settings.formatter.call(self, value, settings);
        $self.html(formattedValue);
      }
    });
  };

  $.fn.countTo.defaults = {
    from: 0, // the number the element should start at
    to: 0, // the number the element should end at
    speed: 1000, // how long it should take to count between the target numbers
    refreshInterval: 100, // how often the element should be updated
    decimals: 0, // the number of decimal places to show
    formatter: formatter, // handler for formatting the value before rendering
    onUpdate: null, // callback method for every time the element is updated
    onComplete: null // callback method for when the element finishes updating
  };

  function formatter(value, settings) {
    return value.toFixed(settings.decimals);
  }
})(jQuery);