function peekaboo(w, d, linkBtnId) {

  // Peekaboo - show-hide toggle
  // Toggle a section using ARIA

  "use strict";
  var openLabel = "Open and skip to navigation bypassing site search";
  var closeLabel = "Close and hide navigation";


  var _getRegionObj = function (linkObj) {
    return d.getElementById(linkObj.hash.replace("#", "")) || !1;
  };


  var _setAriaStates = function (linkObj, regionObj, isExpanded) {
    w.requestAnimationFrame(function () {
      linkObj.setAttribute("aria-expanded", isExpanded);
      regionObj.setAttribute("aria-hidden", !isExpanded);
      linkObj.setAttribute("aria-label", isExpanded ? closeLabel : openLabel);
    });
  };
 

  var _toggleAriaStates = function (e) {

    e.preventDefault();
    var linkObj = e.target;
    var expanded = linkObj.getAttribute("aria-expanded") || !1;

    if (expanded) { // string "false" is boolean true here
      
      var regionObj = _getRegionObj(linkObj);
      if (regionObj) {

        // convert to boolean
        expanded = expanded === "true"; 
        _setAriaStates(linkObj, regionObj, !expanded);
        if (expanded) {
          linkObj.focus();
        } else {

          // Small delay required for focusable object to reappear in DOM
          // (transitionend event would have CSS dependencies)
          setTimeout(function() {
            (regionObj.querySelector("a") || regionObj).focus();
          }, 100);
        }
      }
    }
  };


  var _addAriaAttributes = function (linkObj) {

    var regionObj = _getRegionObj(linkObj);
    if (regionObj) {
      linkObj.setAttribute("aria-controls", regionObj.id);
      regionObj.setAttribute("aria-controlledby", linkObj.id);
      _setAriaStates(linkObj, regionObj, false);
    }
    return regionObj;
  };


  var initialise = function () {

    var anchor = d.getElementById(linkBtnId);
    if (anchor && _addAriaAttributes(anchor)) {
        anchor.addEventListener("click", _toggleAriaStates, !1);
    }
  };

  return initialise();

}

peekaboo(window, document, "hamburger");