sticky sidebar

sticky.js

  function _makeSticky($sticky) {
    var $parent = $sticky.parent();
    var parentOffset = null;
    var myOffset = null;
    $(window).bind('scroll', function () {
      var scroll = $(document.body).scrollTop();
      if (myOffset === null) {
        parentOffset = $parent.offset().top;
        myOffset = $sticky.position().top;
      }
      if (scroll > parentOffset) {
        $sticky.addClass("floating");
        $sticky.css('top', scroll - parentOffset + myOffset);
      } else {
        $sticky.removeClass("floating");
        $sticky.css('top', '');
      }
    });
  }