preserving_scroll_position.js

gistfile1.js

Element.addMethods({
  preservingScrollPosition: function(element, callback) {
    element = $(element);
    var offset = element.cumulativeOffset().top - document.viewport.getScrollOffsets().top;
    callback();
    window.scrollTo(0, element.cumulativeOffset().top - offset);
    return element;
  }
});