function getActiveSibling(el) {
  var elList = el.parentNode.children,
      q = elList.length,
      activeEl = null,
      tmpEl;

  while (q-- && !activeEl) {
    tmpEl = elList[q];
    if (tmpEl !== el && jqLite.hasClass(tmpEl, activeClass)) activeEl = tmpEl
  }

  return activeEl;
}
Get previous active sibling.
@param {Element} el - The anchor element.