Issue 4925 - Create accordion component for Help Center

static/js/main.js

 (function(){
   document.addEventListener("DOMContentLoaded", function()
   {
 
     // Change html class name from "no-js" to "js"
     document.documentElement.className = "js";
 
     // Toggle Navbar Collapse
     function toggleNavbarCollapse()
     {
@@ skipping 36 matching lines @@
       customSelectEls[i]
         .nextElementSibling
         .setAttribute("aria-hidden", "true");
     }
 
     // Accordion menu
 
     function Accordion(accordion)
     {
       this.accordion = accordion;
-      this.init();

[juliandoucette, 2017/09/26 18:57:06]

NIT: It's unnecessary to separate this constructor logic if we are not planning
to override it later (at which point we could separate it).

[ire, 2017/09/28 14:48:52]

Done.

-    }
-
-    Accordion.prototype.init = function()
-    {
+      
       var accordionButtons = this.accordion.getElementsByClassName('accordion-toggle-button');
-      
       for (var i = 0; i < accordionButtons.length; i++)
       {
-        accordionButtons[i]
-          .addEventListener("click", this.toggleAccordionSection, false);
-        accordionButtons[i]
-          .addEventListener("keydown", this.navigateAccordionHeadings, false);
-
         // Close all sections except the first
         if (i !== 0)
         {
           accordionButtons[i].setAttribute("aria-expanded", "false");
           document
             .getElementById( accordionButtons[i].getAttribute("aria-controls") )

[juliandoucette, 2017/10/09 21:18:16]

NIT: Extra whitespace inside brackets

(The same applies elsewhere)

             .setAttribute("hidden", "true");
         }
       }
-    };
 
-    Accordion.prototype.toggleAccordionSection = function()
+      this.accordion
+        .addEventListener("click", this._onClick.bind(this), false);
+      this.accordion
+        .addEventListener("keydown", this._onKeyDown.bind(this), false);
+    }
+
+    Accordion.prototype.toggleSection = function(clickedButton)
     {
       // Hide currently expanded section
-      var accordion = this.parentElement.parentElement;
-      var expandedButton = accordion.querySelector("button[aria-expanded='true']");
+      var expandedButton = this.accordion.querySelector("button[aria-expanded='true']");
       if (expandedButton)
       {
         expandedButton.setAttribute("aria-expanded", "false");
         document
           .getElementById( expandedButton.getAttribute("aria-controls") )
           .setAttribute("hidden", "true");
       }
 
       // If currently expanded section is clicked
-      if (expandedButton === this) return;
+      if (expandedButton === clickedButton) return;
 
       // Expand new section
-      this.setAttribute("aria-expanded", "true");
+      clickedButton.setAttribute("aria-expanded", "true");
       document
-        .getElementById( this.getAttribute("aria-controls") )
+        .getElementById( clickedButton.getAttribute("aria-controls") )
         .removeAttribute("hidden");
     }
 
-    Accordion.prototype.navigateAccordionHeadings = function(event)

[juliandoucette, 2017/09/26 18:57:06]

Suggest:

Accordion.prototype._onKeyDown(event)
{
  if (event.key === "ArrowUp" || event.keyCode === 38) this.toggleNextSection();
  if (event.key === "ArrowDown" || event.keyCode === 40)
this.togglePrevSection();
}

Accordion.prototype.toggleNextSection()
{
  var toggledSectionBody =
this.accordion.querySelector('[aria-expanded="true"]').parentElement.nextElementSibling;

  if (this.accordion.children[this.accordion.children.length - 1] ===
toggledSectionBody) // if the last section is already expanded
     ...  
}

Accordion.prototype.togglePrevSection()
{
  var toggledSectionHeading =
this.accordion.querySelector('[aria-expanded="true"]').parentElement;

  if (this.accordion.children[0] === toggledSectionHeading) // if the first
section is already expanded
     ...  
}
...

(Or similar - I'm just thinking out loud about how this code could be made
clearer.)

[ire, 2017/09/28 14:48:53]

Made some changes.

+    Accordion.prototype.focusNextSection = function()
     {
-      var IS_KEY_UP = event.key == 38 || event.keyCode == 38;

[juliandoucette, 2017/09/26 18:57:06]

I think that the value of event.key for up is "ArrowUp" and down is "ArrowDown".

[ire, 2017/09/28 14:48:53]

Done. (Sorry I didn't check :/)

-      var IS_KEY_DOWN = event.key == 40 || event.keyCode == 40;
+      var currentFocus = document.activeElement;
+      var nextheading = currentFocus.parentElement.nextElementSibling.nextElementSibling;
 
-      if (!IS_KEY_UP && !IS_KEY_DOWN) return;
+      if (nextheading)
+      {
+        nextheading // .accordion-heading
+          .firstElementChild // .accordion-toggle-button
+          .focus();
+      }
+      else
+      {
+        this.accordion
+          .firstElementChild // .accordion-heading
+          .firstElementChild // .accordion-toggle-button
+          .focus();
+      }
+    }
 
-      var accordion = this.parentElement.parentElement;
+    Accordion.prototype.focusPrevSection = function()
+    {
+      var currentFocus = document.activeElement;
+      var prevAccordionBody = currentFocus.parentElement.previousElementSibling;
 
-      if (IS_KEY_UP)
+      if (prevAccordionBody)
       {
-        var prevAccordionBody = this.parentElement.previousElementSibling;
-        if (prevAccordionBody)
-        {
-          prevAccordionBody // .accordion-body
-            .previousElementSibling // .accordion-heading
-            .firstElementChild // .accordion-toggle-button
-            .focus();
-        }
-        else
-        {
-          accordion
-            .lastElementChild // .accordion-body
-            .previousElementSibling // .accordion-heading
-            .firstElementChild // .accordion-toggle-button
-            .focus();
-        }
+        prevAccordionBody // .accordion-body
+          .previousElementSibling // .accordion-heading
+          .firstElementChild // .accordion-toggle-button
+          .focus();
       }
+      else
+      {
+        this.accordion
+          .lastElementChild // .accordion-body
+          .previousElementSibling // .accordion-heading
+          .firstElementChild // .accordion-toggle-button
+          .focus();
+      }
+    }
 
-      else if (IS_KEY_DOWN)
+    Accordion.prototype._onKeyDown = function(event)
+    {
+      if (!event.target.classList.contains("accordion-toggle-button")) return;
+
+      if (event.key == "ArrowUp" || event.keyCode == 38)
       {
-        var nextheading = this.parentElement.nextElementSibling.nextElementSibling;
-        if (nextheading)
-        {
-          nextheading // .accordion-heading
-            .firstElementChild // .accordion-toggle-button
-            .focus();
-        }
-        else
-        {
-          accordion
-            .firstElementChild // .accordion-heading
-            .firstElementChild // .accordion-toggle-button
-            .focus();
-        }
+        this.focusPrevSection();
       }
+      else if (event.key == "ArrowDown" || event.keyCode == 40)
+      {
+        this.focusNextSection();
+      }
+    }
 
+    Accordion.prototype._onClick = function(event)
+    {
+      if (!event.target.classList.contains("accordion-toggle-button")) return;
+      
+      this.toggleSection(event.target);
     }
 
     var accordions = document.getElementsByClassName('accordion');
     for (var i = 0; i < accordions.length; i++)
     {
       new Accordion(accordions[i]);
     }
 
   }, false);
 }());