FAQ using ARIA attributes to meet WCAG 2 level AA [without a button]

/*Downloaded from https://www.codeseek.co/2kool2/faq-using-aria-attributes-to-meet-wcag-2-level-aa-without-a-button-RJaBYP */
    body{
  padding: 0;
  font-weight:100;
  scroll-behavior: smooth;
}


/* FAQ container */

.dl-faq {
  position: relative;
  max-width: 36rem;
  margin: 2rem auto 3rem;
}

.dl-faq > dt {
  font-size: 1.2rem;
  font-weight: 100;
  padding: 1rem;

  /* Fix for IE9 & 10 */
  border-top: 1px solid rgba(255,255,255,.2);
}

dt > .pab-btn {
  color: inherit;
  background-color: inherit;
}
.dl-faq > dt:first-child .pab-btn,
.dl-faq > dt:first-child {
  border-top: 0;
}

.dl-faq.pab_container > dt {
  /* added via JS */
  padding: 0;
}

.dl-faq > dd {
  margin: 0 auto;
  padding: 0 1.5em;
  font-weight:100;
}

.dl-faq > dd > div {
  padding: 0 0 2rem;
}

.dl-faq div > p {
  margin: 0 0 1rem;
}

.dl-faq div >:last-child {
  margin: 0;
}


/* The acivating buttons added via JS */

.pab-btn {
  position: relative;
  display: inline-block; /* added to support span[role=button] */
  cursor: pointer;
  transition: color .3s ease-in;

  /* Using absolute positioning for SVG so reserve some space */
  padding: 1rem 2.5rem 1rem .5rem;
  border: 0 solid transparent;
  border-top: 1px solid rgba(0,0,0,.75);

  /* inherit doesn't work in IE */
  font-size: inherit;
  text-align: left;
  width: 100%;
}

.pab-btn:hover,
.pab-btn:focus,
.pab-btn:active {
  color:#fff;
  background-color: rgba(0,0,0,.25);
}

.pab-btn:focus {
  outline: 0 solid;
}

.pab-btn::-moz-focus-inner {
  border: 0;
  padding: 0;
  margin-top: -2px;
  margin-bottom: -2px;
}


/* Underline text on button hover (Tesco requirement) */

.pab-btn > span {
  position: relative;
  /* Removes button drepression in IE */
  pointer-events: none;
  /* Required by Safari */
  border-bottom: 1px solid transparent;
  transition: border-color .3s;
}

.pab-btn:hover > span,
.pab-btn:focus > span {
  border-bottom-color: rgba(255,255,255,.5);
}

.pab-btn:active > span {
  border-bottom-color: transparent;
}


/* SVG plus */

.pab-svg-plus {
  /* Tesco requirement
  border: 2px solid currentColor; */
  border-radius: 100%;
  display: block;
  position: absolute;
  top: calc(50% - .75em);
  right: 4px;
  width: 1.5em;
  height: 1.5em;
  margin: 0;
  pointer-events: none;
  stroke-width: 4;
  stroke-linecap: square;
  stroke: currentColor;
  -webkit-transition: transform .7s ease-out, box-shadow .3s ease-out;
  transition: transform .7s ease-out, box-shadow .3s ease-out;
}

.pab-btn:hover .pab-svg-plus,
.pab-btn:focus .pab-svg-plus {
  /* Same colour as text but with .4 alpha */
  /* Tesco requirement
  box-shadow: 0 0 0 4px rgba(0, 83, 159, 0.4);*/
}

.pab-btn:active .pab-svg-plus {
  /* Tesco requirement
  box-shadow: 0 0 0 4px rgba(0, 83, 159, 0);*/
}

[aria-expanded="true"] > .pab-svg-plus {
  transform: rotateZ(360deg);
}

.use-plus {
  /* used to animate plus into minus */
  -webkit-transition: stroke .5s ease-out, opacity .7s ease-out;
  transition: stroke .5s ease-out, opacity .7s ease-out;
}

[aria-expanded=true] .use-plus {
  opacity: 0;
}

.isSafari .pab-btn .pab-svg-plus {
  box-shadow: none;
}


/* Open / close animation - The inaccurate CSS max-height is resolved via JS adding an inline style */

[data-pab] + [aria-hidden] {
  overflow: hidden;
  opacity: 1;
  max-height: 50rem;
  visibility: visible;
  transition: visibility 0s ease 0s, max-height .65s ease-out 0s, opacity .65s ease-in 0s;
}

[data-pab] + [aria-hidden="true"] {
  max-height: 0;
  opacity: 0;
  visibility: hidden;
  transition-delay: .66s, 0s, 0s;
}


/* Overide the max-height set as an inline style by the JS */

[data-pab] + [style][aria-hidden="true"] {
  max-height: 0 !important;
}

/*Downloaded from https://www.codeseek.co/2kool2/faq-using-aria-attributes-to-meet-wcag-2-level-aa-without-a-button-RJaBYP */
    
// https://john-dugan.com/javascript-debounce/
// https://codepen.io/johndugan/pen/BNwBWL?editors=001
var debounce = function(func, wait, immediate) {

  "use strict";

  var timeout;
  return function() {
    var context = this;
    var args = arguments;
    var later = function() {
      timeout = null;
      if ( !immediate ) {
        func.apply(context, args);
      }
    };
    var callNow = immediate && !timeout;
    clearTimeout(timeout);
    timeout = setTimeout(later, wait || 200);
    if ( callNow ) {
      func.apply(context, args);
    }
  };
};



// peek-a-boo.7.3.js - Mike Foskett - https://websemantics.uk/articles/peek-a-boo-v7/

// Show - hide a block - adapted for FAQ
// Requires:
//    setAttribute / getAttribute (IE9+)
//    classList (IE10+)  - disabled
//    addEventListener (IE9+)
//    requestAnimationFrame (IE10+) - replace with requestAF() for IE9
//    querySelectorAll
//    preventDefault
//    debounce()

	

// FAQ version:
// v7.4.1 Changed: use a span instead of button
// v7.4 Added: open an question from an internal anchor
// v7.3 Expanded when URI fragment matches the target ID
// v7.2 HTML button reinstated, js adjusted.
//			Initial open/close state reworked


var Pab = (function (window, document, debounce) {
	
	// Terminology used:
	// toggle - The dynamically added button used to toggle the hidden content
	// target - The object which contains the hidden content
	// toggleParent - The object which will, or does, contain the toggle button

  "use strict";

  var dataAttr = "data-pab";
  var attrName = dataAttr.replace("data-", "") + "_";
  var btnClass = dataAttr.replace("data-", "") + "-btn";
	var dataExpandAttr = dataAttr + "-expand";
  var internalId = 1;


  function $ (selector) {
    return Array.prototype.slice.call(document.querySelectorAll(selector));
  }


  function _isExpanded (obj) { // or not aria-hidden
    return obj && (obj.getAttribute("aria-expanded") === "true" || obj.getAttribute("aria-hidden") === "false");
  }


	// This function is globally reusable. Perhaps externalise for reuse?  
	// Get height of an element object
  // Assumes it is hidden by max-height: 0 in the CSS
	var _getHiddenObjectHeight = function (obj) {
    obj.setAttribute("style", "max-height: none");
		var height = obj.scrollHeight;
    obj.removeAttribute("style");
		return height;
	};

  var _openCloseToggleTarget = function (toggle, target, isExpanded) {
    toggle.setAttribute("aria-expanded", !isExpanded);
    _setToggleMaxHeight(target);
    window.requestAnimationFrame(function(){
      target.setAttribute("aria-hidden", isExpanded);
    });
  };


  var _setToggleMaxHeight = function (target) {
    if (_isExpanded(target)) {
      // max-height overidden by CSS !important
      // target.style.maxHeight = 0;
    } else {
      target.style.maxHeight = _getHiddenObjectHeight(target) + "px";
    }
  };

  var _toggleClicked = function (event) {

    var toggle = event.target;
    var target;
    var isExpanded;

    if (toggle) {

			// To prevent children bubbling up to parent causing more than one click event
			event.stopPropagation();

      target = document.getElementById(toggle.getAttribute("aria-controls"));
      if (target) {
        isExpanded = _isExpanded(toggle);
        _openCloseToggleTarget(toggle, target, isExpanded);
      }
      event.preventDefault();
    }
  };
	

  var _keypressed = function (e) {
    if (e.keyCode === 32 || e.keyCode === 13) { // space || enter
      e.stopPropagation();
      _toggleClicked(e);
      e.preventDefault();
    }
  };


  var _addToggleListeners = function (toggle) {

    toggle.addEventListener("keydown", _keypressed, false);
    
    // Add enter and space to allow keyboard activation
    toggle.addEventListener("click", _toggleClicked, false);

  };


  var _setUpToggle = function (toggle) {

		// Create a html span to use as a button, add content from parent, replace original parent content.
		var btn = document.createElement("span");

    // Make the span a button equivalent
		btn.setAttribute("role", "button");
    btn.setAttribute("tabindex", "0");
		
		btn.className = btnClass;
		btn.innerHTML = toggle.innerHTML;
		btn.setAttribute("aria-expanded", false);
		btn.setAttribute("id", attrName + internalId++);
		btn.setAttribute("aria-controls", toggle.getAttribute(dataAttr));

		toggle.innerHTML = "";
		toggle.appendChild(btn);
		
		return btn;
	};


	// Prestating the container class in the HTML allows the CSS to render before JS kicks in.
	// Add container class to parent if not prestated
  var _setUpToggleParent = function (toggle) {
    var parent = toggle.parentElement;
    if (parent && !parent.className.match(attrName + "container")) {
      //parent.classList.add(attrName + "container");
      parent.className += " " + attrName + "container";
    }
  };


  var _addToggleSVG = function (toggle) {
    var clone = toggle.cloneNode(true);
    if (!clone.innerHTML.match("svg")) {

			// HTML SVG definition allows more control
      clone.innerHTML += "<svg role=presentational focusable=false class=" + dataAttr.replace("data-", "") + "-svg-plus><use class=\"use-plus\" xlink:href=\"#icon-vert\" /><use xlink:href=\"#icon-hori\"/></svg>";
      //requestAnimationFrame(function () {
        toggle.parentElement.replaceChild(clone, toggle);
      //});
    }
    return clone;
  };


  var _setUpTargetAria = function (toggle, target) {
    target.setAttribute("aria-hidden", !_isExpanded(toggle));
    target.setAttribute("aria-labelledby", toggle.id);
  };


  var _resetAllTargetsMaxHeight = function () {
    var toggles = document.querySelectorAll("[" + dataAttr + "]");
    var i = toggles.length;
    var target;
    while (i--) {
      target = document.getElementById(toggles[i].getAttribute(dataAttr));
      if (target) {
        target.style.maxHeight = _getHiddenObjectHeight(target) + "px";
      }
    }
  };


	var isMustardCut = function () {
		return (document.querySelectorAll && document.addEventListener);
	};


	var _openIfRequired = function (toggle, target) {
		
		var fragmentId = window.location.hash.replace("#", "");
		
		// Expand by default "data-pab-expand" small delay applied
		if (toggle.parentElement.hasAttribute(dataExpandAttr)) {
			setTimeout(function () {
				_openCloseToggleTarget(toggle, target, _isExpanded(toggle));
			}, 500);
		}
    

		// Check url fragment and if target ID matches, open it
		if (target.id === fragmentId) {
			setTimeout(function () {
				_openCloseToggleTarget(toggle, target, false);
				toggle.focus();
			}, 500);
		}

	};


	var addSingleToggleTarget = function (toggleParent) {

		var targetId = toggleParent.getAttribute(dataAttr);
		var target = document.getElementById(targetId);
		var toggle;

		if (target && isMustardCut) {
			toggle = _setUpToggle(toggleParent);
			_setUpToggleParent(toggleParent);
			toggle = _addToggleSVG(toggle);
			_setUpTargetAria(toggle, target);
			_addToggleListeners(toggle);
			_openIfRequired(toggle, target);
		}
	};
  
  var hashChanged = function (e) {
    var fragmentId = window.location.hash.replace("#", "");
    var toggle = document.querySelector("#" + fragmentId + " > ." + btnClass);
    var target = document.getElementById(toggle.getAttribute("aria-controls"));
    if (!toggle || !target) {return false;}

    toggle.focus();
    toggle.scrollIntoView({behavior: "smooth", block: "start", inline: "nearest"});

    _openCloseToggleTarget(toggle, target, false);
  };


  var addToggles = function () {

		// Iterate over all toggles (elements with the "data-pab" attribute)
		var togglesMap = $("[" + dataAttr + "]").reduce(function (temp, toggleParent) {
			addSingleToggleTarget(toggleParent);
			return true;
		}, {});

    return true;
  };


	if (isMustardCut) {
		window.addEventListener("load", addToggles, false);

		// Recalculate all target max-heights after (debounced) window is resized.
		window.addEventListener("resize", debounce(_resetAllTargetsMaxHeight, 500), false);
    
    // On fragment change
		window.addEventListener("hashchange", hashChanged, false);
	}


  return {
    // Exposes an addition function to the global scope allowing toggle & target to be added dynamically.
		add: addSingleToggleTarget
  };


}(window, document, debounce));

// To add dynamically created toggles:
// Pab.add(toggle-object); // Add individual toggle & target