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                <h1>Animated <abbr title="Accessible Rich Internet Applications">ARIA</abbr> hamburger menu to meet <abbr title="Web Content Accessibility Guidelines">WCAG</abbr> 2 level AA</h1>

<p>I needed a non-linear show-hide peekaboo to meet WCAG 2 level AA.<br> This one ticks the boxes, and a reusable asset to boot.</p>

<p>JavaScript is used to toggle ARIA states and control tab position while CSS attribute selectors control animation.<p>

  <a id="hamburger" href="#navigation" class="menu">
    <svg class="menu_svg" viewbox="0 0 48 48">
      <rect x="15.5" y="16.5" width="20" height="3"/>
      <rect x="15.5" y="23.5" width="20" height="3"/>
      <rect x="15.5" y="30.5" width="20" height="3"/>

<p>A <a href="#">Fake Site Search</a> between the Menu link and the navigation block.<br>Arrgh, the things you have to deal with&hellip;</p>

<nav id="navigation" class="navigation">
  <h2 class=navigation_title>Main navigation:</h2>
  <ul class=navigation_list>
    <li><a href="#"></a></li>
    <li><a href="#">Groceries</a></li>
    <li><a href="#">Tesco direct</a></li>
    <li><a href="#">F&amp;F clothing</a></li>
    <li><a href="#">Clubcard</a></li>
    <li><a href="#">Tesco Bank</a></li>
    <li><a href="#">Wine by the case</a></li>
    <li><a href="#">Tesco Mobile</a></li>

<p><a href="#">Fake link after navigation block</a> to test keyboard <kbd>Tab</kbd> order.</p>

<p>Strongly influenced by the work of Heydon Pickering</p>



                /* Simple animated Peekaboo show-hide */

/* Generic styling (not required) */

.menu {
  width: 40px;
  height: 40px;
  border: 0 solid;

.menu_svg {
  pointer-events: none;

.menu[aria-expanded="true"] {
  background-color: #1A1A1A;
  fill: #fff;

/* The heavy lifting is done by  3 statements */

.navigation {
  position: relative;
  margin: 0;
  padding: 0;
  transform: translate3d(0,0,0);
  backface-visibility: hidden;

  /* opacity has to finish before height to allow JS time to find first link */
  transition: visibility 0s ease-out, opacity .3s linear, max-height .5s ease-out;
  opacity: 0;
  visibility: hidden;
  max-height: 0;
  overflow: hidden;

.navigation[aria-hidden="true"] {
  transition-delay: .6s, 0s, 0s;

.navigation[aria-hidden="false"] {
  transition-delay: 0s, 0s, 0s;
  opacity: 1;
  visibility: visible;
  max-height: 12em;

/* More generic styling */

.navigation_title {
  margin: 0;
  padding: 0;
  position: absolute;
  left: -200em;

.navigation_list {
  margin: 0;
  padding: 0 2em;

.navigation_list li {
  width: 50%;
  float: left;


                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) {

    var linkObj =;
    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) {
        } 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) {
      _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");