Divide summary and show/hide text with punctuation

Insert a comma after the summary line in the markup, similar to the punctuation inserted after the heading.

The GDS accessibility clinic gave us the feedback that the punctuation symbol which was originally introduced to improve NVDA announcements also improves the semantics of the button text in general by dividing up its content thematically. See #2327 (comment)

src/govuk/components/accordion/accordion.js

@@ -118,13 +118,6 @@ Accordion.prototype.initHeaderAttributes = function ($headerWrapper, index) {
   var $showIcons = document.createElement('span')
   $showIcons.classList.add(this.sectionShowHideToggleClass)
 
-  // Add pause (with a comma) after heading for assistive technology.
-  // Example: [heading]Section A ,[pause] Show this section.
-  // https://accessibility.blog.gov.uk/2017/12/18/what-working-on-gov-uk-navigation-taught-us-about-accessibility/
-  var $srPause = document.createElement('span')
-  $srPause.classList.add('govuk-visually-hidden')
-  $srPause.innerHTML = ', '
-
   // Wrapper of heading to receive focus state design
   // ID set to allow the heading alone to be referenced without "this section"
   var $wrapperFocusHeading = document.createElement('span')
@@ -151,7 +144,7 @@ Accordion.prototype.initHeaderAttributes = function ($headerWrapper, index) {
   $heading.removeChild($span)
   $heading.appendChild($button)
   $button.appendChild($wrapperFocusHeading)
-  $button.appendChild($srPause)
+  $button.appendChild(this.getButtonPunctuationEl())
   // span could contain HTML elements (see https://www.w3.org/TR/2011/WD-html5-20110525/content-models.html#phrasing-content)
   $wrapperFocusHeading.innerHTML = $span.innerHTML
 
@@ -174,6 +167,7 @@ Accordion.prototype.initHeaderAttributes = function ($headerWrapper, index) {
     $summary.parentNode.replaceChild($summarySpan, $summary)
 
     $button.appendChild($summarySpan)
+    $button.appendChild(this.getButtonPunctuationEl())
   }
 
   $button.appendChild($showIcons)
@@ -327,4 +321,23 @@ Accordion.prototype.setInitialState = function ($section) {
   }
 }
 
+/**
+* Create an element to improve semantics of the section button with punctuation
+* @return {object} DOM element
+*
+* Used to add pause (with a comma) for assistive technology.
+* Example: [heading]Section A ,[pause] Show this section.
+* https://accessibility.blog.gov.uk/2017/12/18/what-working-on-gov-uk-navigation-taught-us-about-accessibility/
+*
+* Adding punctuation to the button can also improve its general semantics by dividing its contents
+* into thematic chunks.
+* See https://github.com/alphagov/govuk-frontend/issues/2327#issuecomment-922957442
+*/
+Accordion.prototype.getButtonPunctuationEl = function () {
+  var $punctuationEl = document.createElement('span')
+  $punctuationEl.classList.add('govuk-visually-hidden')
+  $punctuationEl.innerHTML = ', '
+  return $punctuationEl
+}
+
 export default Accordion