(function (jQuery) {

    /**
    * Function for setting offset, created here so it's only created once rather than
    * creating an anonymous function every time offset is called
    */
    function setOffset(el, newOffset) {
        var $el = jQuery(el);

        // get the current css position of the element
        var cssPosition = $el.css('position');

        // whether or not element is hidden
        var hidden = false;

        // if element was hidden, show it
        if ($el.css('display') == 'none') {
            hidden = true;
            $el.show();
        }

        // get the current offset of the element
        var curOffset = $el.offset();

        // if there is no current jQuery offset, give up
        if (!curOffset) {
            // if element was hidden, hide it again
            if (hidden)
                $el.hide();
            return;
        }

        // set position to relative if it's static
        if (cssPosition == 'static') {
            $el.css('position', 'relative');
            cssPosition = 'relative';
        }

        // get current 'left' and 'top' values from css
        // this is not necessarily the same as the jQuery offset
        var delta = {
            left: parseInt($el.css('left'), 10),
            top: parseInt($el.css('top'), 10)
        };

        // if the css left or top are 'auto', they aren't numbers
        if (isNaN(delta.left)) {
            delta.left = (cssPosition == 'relative') ? 0 : el.offsetLeft;
        }
        if (isNaN(delta.top)) {
            delta.top = (cssPosition == 'relative') ? 0 : el.offsetTop;
        }

        if (newOffset.left || 0 === newOffset.left) {
            $el.css('left', newOffset.left - curOffset.left + delta.left + 'px');
        }
        if (newOffset.top || 0 === newOffset.top) {
            $el.css('top', newOffset.top - curOffset.top + delta.top + 'px');
        }

        // if element was hidden, hide it again
        if (hidden)
            $el.hide();
    }

    jQuery.fn.extend({

        /**
        * Store the original version of offset(), so that we don't lose it
        */
        _offset: jQuery.fn.offset,

        /**
        * Set or get the specific left and top position of the matched
        * elements, relative the the browser window by calling setXY
        * @param {Object} newOffset
        */
        offset: function (newOffset) {
            return !newOffset ? this._offset() : this.each(function () {
                setOffset(this, newOffset);
            });
        }
    });

})(jQuery);