WAI-ARIA An introduction to Accessible Rich Internet Applications / AccessU 2018

Vanilla HTML is limiting and boring. Our clients demand highly engaging and interactive web experiences. And wouldn’t you know, with just a bit of HTML and JavaScript we can craft amazing custom controls, widgets and effects that go far beyond the confines of traditional static markup. But how can we ensure that these custom experiences are both understandable and usable for people with disabilities, and in particular those using assistive technologies such as screen readers?

In this talk, we will look at the basics of making some common custom-built components accessible - covering how browsers and assistive technologies interact, the limitations of HTML, and how ARIA can help make interactive experiences more accessible. In addition, we will explore some of the recent additions in ARIA 1.1, as well as some particular challenges when it comes to traditional ARIA patterns and assistive technologies on mobile/tablet/touch devices.

Evergreen slidedeck at https://patrickhlauke.github.io/aria/presentation/ / https://github.com/patrickhlauke/aria/

Transcript

1. wai-aria AN INTRODUCTION TO ACCESSIBLE RICH INTERNET APPLICATIONS Patrick H. Lauke / The Paciello Group / AccessU / 15 May 2018
2. what is ARIA and why do we need it ?
3. the problem it's "easy" (in most cases) to make static web content accessible, but nowadays the web strives to be an application platform complex web applications require structures (e.g. interactive controls) that go beyond what regular HTML offers (though some of this introduced with HTML5 ... more on that later)
4. jQuery UI
5. Polymer Project
6. the problem when building interactive controls, some (too many) web developers go "all out" on the JavaScript/CSS, but ignore/sidestep regular HTML controls completely
7. code examples here are simplified (but will hopefully convey the right concepts)
8. <div onclick="...">Test</div> faked button for a sighted mouse / touchscreen user this is a button... but what about keyboard users?
9. <div tabindex="0" onclick="...">Test</div> faked button with focus now we can at least focus it... but can we activate it?
10. <div tabindex="0" onkeyup="..." onclick="...">Test</div> faked button with focus and keyboard handling for a sighted mouse / touchscreen / keyboard user this is a button... but what about assistive technology users?
11. compare <div> to a real <button> faked button versus real <button>
12. "test" versus "test button – to activate press SPACE bar"
13. the problem generic/inappropriate HTML elements, with extra JavaScript/CSS on top...but they're still recognised and exposed as <span> , <div> , etc
14. the interplay of browser and assistive technology
15. Operating systems and other platforms provide interfaces that expose information about objects and events to assistive technologies Java Accessibility API [JAPI], Microsoft Active Accessibility [MSAA], the Mac OS X Accessibility Protocol [AXAPI], the Gnome Accessibility Toolkit (ATK) [ATK], and IAccessible2 [IA2]
16. Marco Zehe: Why accessibility APIs matter
17. assistive technologies
18. assistive technologies •  NVDA (free) •  Narrator (free) •  JAWS •  ZoomText •  Dragon NaturallySpeaking •  VoiceOver (free) •  TalkBack (free) •  ...
19. inspection tools
20. inspection tools test using assistive technologies (e.g. screenreaders), however... assistive technologies often use heuristics to repair incomplete/broken accessibility API information - so we want to check what's actually exposed to the OS/platform. of course, browsers also have bugs/incomplete support...
21. Firefox Accessibility Inspector (version 61+) (enable devtools.accessibility.enabled in about:config )
22. chrome://accessibility view of the raw accessibility tree
23. Accessibility Viewer (aViewer)
24. James Craig - Using ARIA 1.0 and the WebKit Accessibility Node Inspector
25. Xcode Accessibility Inspector (but for Chrome, remember to turn on accessibility mode in chrome://accessibility)
26. compare <div> to a real <button> faked button versus real <button>
29. if you use custom (not standard HTML) widgets, use ARIA to ensure correct info is exposed
30. what is ARIA?
31. W3C - Accessible Rich Internet Applications (WAI-ARIA) 1.1
32. ARIA defines HTML attributes to convey correct role, state, properties and value
33. at a high level, ARIA defines various role and aria-* attributes that can be added to your markup
34. W3C - WAI-ARIA 1.1 - 5.3 Categorization of Roles the whole model is vast and complex...and thankfully you don't need to remember this
35. Roles are categorized as follows: •   Abstract Roles: never used in markup directly - they serve only for the categorization/definitions •   Widget Roles: interactive controls - simple or composite (made up of various components) •   Document Structure Roles: define what content/structures represent (e.g. headings, lists, groups) •   Landmark Roles: identify key parts of a document/page •   Live Region Roles: special areas of the page whose content is dynamically updated and should be announced by AT •   Window Roles: content that acts as a separate window (dialogs)
36. each role has "states and properties" (e.g. ARIA 1.1 definition for button ) implicit/inherited or defined via aria-* attributes
37. this is all complex and confusing...
38. as my former colleague Karl Groves succintly put it, ARIA helps answer the questions: what is this thing and what does it do?
39. what information does ARIA provide? •   role: what type of "thing" is this? (e.g. 'button', 'main content') •   state: what is its situation? (e.g. 'disabled', 'checked', 'expanded') •   name: what is its name/label? •   relationship: is it tied to any other elements in the page somehow? this information is mapped by the browser to the operating system's accessibility API and exposed to assistive technologies. extra benefit: once AT understands meaning/purpose, it can automatically announce specific hints and prompts (e.g. JAWS "... button - to activate, press SPACE bar")
40. <div tabindex="0" role="button" onkeyup="..." onclick="...">Test</div> faked button with appropriate role
42. use ARIA to: •  make custom widgets understandable to assistive technology users •  programmatically indicate relationships between elements •  notify users of dynamic updates •  hide irrelevant visible content from assistive technology •  remediation of inaccessible content without completely recoding
43. ARIA roles and attributes: restrictions •  certain role s only make sense as part of a specific complex widget •  some aria-* attributes are global •  other aria-* attributes only make sense for particular role •  not all roles/attributes are supported/implemented consistently everywhere
44. what ARIA doesn't do... ARIA is not magic : it only changes how assistive technology interprets content. specifically, ARIA does not : •  make an element focusable •  provide appropriate keyboard bindings •  change browser behavior •  automatically maintain/update properties •  change visible appearance all of this is still your responsibility...
45. ARIA support •  Browsers: Firefox 3+, Internet Explorer 8+, Safari 4+ (Mac), Chrome 17+, ... •  Assistive technologies: JAWS 8+, Windows Eyes 5.5+, ZoomText, VoiceOver, TalkBack, NVDA, ORCA, ...
46. "support" does not mean that everything works, though...
47. in principle ARIA can be used in all markup languages (depending on browser support )
48. Using ARIA to enhance SVG accessibility
49. ...but we'll just focus on ARIA in HTML
50. W3C - ARIA in HTML
51. W3C - Using ARIA
52. the 5 rules of ARIA use
53. 1. don't use ARIA
55. If you can use a native HTML element [HTML5] or attribute with the semantics and behaviour you require already built in, instead of re- purposing an element and adding an ARIA role, state or property to make it accessible, then do so. “
56. you can use a <span> to behave as, and be exposed just like, a link... <span tabindex="0" role="link" onclick="document.location='...'" onkeyup="..." >link</span> example: link ...but why would you? unless there's a very good reason, just use <a href="...">...</a>
57. 2. don't change native semantics unless you really have to / know what you're doing
58. don't do this: <h1 role="button">heading button</h1> do this instead: <h1><span role="button">heading button</span></h1> otherwise the heading is no longer a heading (e.g. AT users can't navigate to it quickly)
59. don't do this: <ul role="navigation"> <li><a href="...">...</a></li> ... </ul> do this instead: <div role="navigation"> <ul> <li><a href="...">...</a></li> ... </ul> </div> otherwise the list is no longer a list (e.g. AT won't announce "list with X items...")
60. 3. make interactive ARIA controls keyboard accessible
61. All interactive widgets must be focusable and scripted to respond to standard key strokes or key stroke combinations where applicable. [...] Refer to the keyboard and structural navigation and design patterns and widgets sections of the WAI-ARIA 1.1 Authoring Practices
62. 4. don't "neutralise" focusable elements
63. don't use role="presentation" or aria-hidden="true" on a visible focusable element. Otherwise, users will navigate/focus onto "nothing". <!-- don't do this... --> <button role="presentation">press me</button> <button aria-hidden="true">press me</button> <span tabindex="0" aria-hidden="true">...</span>
64. 5. interactive elements must have an accessible name
65. <!-- don't do this... --> <span tabindex="0" role="button"> <span class="glyphicon glyphicon-remove"></span> </span>
66. <span tabindex="0" role="button"> <span class="glyphicon glyphicon-remove"> <span class="...">Delete</span> </span> </span> <span tabindex="0" role="button" title="Delete" > <span class="glyphicon glyphicon-remove"></span> </span> refer to WAI-ARIA 1.1 - 5.2.7. Accessible Name Calculation
67. <span tabindex="0" role="button" aria-label="Delete" > <span class="glyphicon glyphicon-remove"></span> </span> <span tabindex="0" role="button" aria-labelledby="..." > <span class="glyphicon glyphicon-remove"></span> </span> ... <span id=" ... " class="...">Delete</span> refer to WAI-ARIA 1.1 - 5.2.7. Accessible Name Calculation
68. Chrome DevTools' accessibility panel can help understand which attributes contribute to an element's name (example)
69. WAI-ARIA spec can be dry/technical - use for reference W3C - WAI-ARIA 1.1 Authoring Practices more digestible.
70. ARIA and HTML5
71. ARIA is used when building/denoting things that native HTML can't do
72. HTML5 introduced new elements, element types, attributes that solve some of these situations
73. example: HTML5 slider
74. W3C HTML Accessibility API Mappings 1.0
75. HTML5 accessibility
76. HTML5 now also includes WAI-ARIA ...
77. ...and you can validate pages with (static) ARIA validator.w3.org
78. common structures and widgets (not an exhaustive list - enough to understand concepts)
79. using ARIA to provide structure
80. <p class="1" role="heading" aria-level="1" >Heading 1</p> ... <p class="h2" role="heading" aria-level="2" >Heading 2</p> ... <p class="h3" role="heading" aria-level="3" >Heading 3</p> ... example: headings •  add role="heading" •  if more than one hierarchical level, and can't be inferred from structure, add explicit aria-level
81. <div role="list" > <div role="listitem" >...</div> <div role="listitem" >...</div> <div role="listitem" >...</div> ... </div> example: list/listitem •  add role="list" and role="listitem" •  generally more complex (big markup structures that boil down to essentially "a list of things...")
82. removing semantics
83. if your page/app uses inappropriate markup, ARIA can be used to remove semantic meaning. useful for remediation if markup cannot be changed. <table role="presentation" > <tr> <td>Layout column 1</td> <td>Layout column 2</td> </tr> </table> example: layout table remediation ARIA 1.1 introduced role="none" as an alias for role="presentation" – they are equivalent (and older browsers/AT likely better off still using role="presentation" )
84. landmarks
85. adapted from HTML5 Doctor - Designing a blog with html5 example: blog structure
87. why define landmarks? •  users of assistive technologies can more easily find areas of your page/app •  AT keyboard controls to navigate to/between landmarks •  overview dialogs listing all landmarks (e.g. NVDA)
88. example: blog structure with ARIA
89. doesn't HTML5 solve this?
90. adapted from HTML5 Doctor - Designing a blog with html5 example: blog structure with HTML5
92. using ARIA for simple/standalone widgets
93. my JavaScript sucks... (but will hopefully convey the right concepts)
94. button
95. <span class="...">Button?</span> <div class="...">Button?</div> <a href="#" class="...">Button?</a> example: button while using a link is slightly less evil, as at least it receives keyboard focus by default, it's still not correct: links are meant for navigation , not in-page actions or form submissions
96. <span tabindex="0" class="..." role="button" >Button!</span> <div tabindex="0" class="..." role="button" >Button!</div> <a href="#" class="..." role="button" >Button!</a> •  add role="button" •  make sure it's focusable •  add handling of SPACE (and in some cases ENTER )
97. assuming there's a click handler: foo.addEventListener('keyup', function(e) { // Space key if (e.keyCode === 32) { // stop default behavior (usually, scrolling) e.preventDefault(); // trigger the existing click behavior this.click(); } });
98. you could even do it "in one go" for all your faked buttons, assuming they have the correct role="button" , with querySelectorAll and attribute selectors: var buttons = document.querySelectorAll("[role='button']"); for (var i=0; i<buttons.length; i++) { buttons[i].addEventListener('keyup', function(e) { if (e.keyCode === 32) { e.preventDefault(); this.click(); } }); }
99. toggle button
100. •  default HTML does not offer a simple on/off toggle •  "CSS only" <input type="checkbox"> hacks – but these may be confusing to AT users/not always appropriate •  ARIA can be used to enhance native elements – start off with closest match, like an actual <button> , and extend from there
101. let's assume we implement this with JavaScript to purely add a CSS classname: <button class="...">Toggle</button> <button class="... toggled ">Toggle</button> example: toggle in real applications, you'll likely keep track of the state in some additional way – this is only for illustrative purposes
102. <button class="..." aria-pressed="false" >Toggle</button> <button class="... toggled " aria-pressed="true" >Toggle</button> foo.getAttribute("aria-pressed"); foo.setAttribute("aria-pressed", "true"); foo.setAttribute("aria-pressed", "false"); add aria-pressed and dynamically change its value example: toggle with aria-pressed •  these are HTML attributes and must be read/written using getAttribute() / setAttribute() •  and even boolean attributes take string values
103. <button class="... " aria-pressed="true" >Toggle</button> button[aria-pressed="true"] { ... } •  bonus: use CSS attribute selectors – no need for extra CSS class (this also helps debugging – easier to spot visually when ARIA roles/properties aren't correctly set) example: toggle with aria-pressed and simplified CSS toggled button.toggled { ... }
104. if your actual label text changes when toggling, aria-pressed is likely not necessary (could actually be more confusing for user) <button ...>Mute</button> if (...) { this.innerHTML = "Mute"; ... } else { this.innerHTML = "Unmute"; ... } example: toggle with a changing name/label
105. checkbox
106. <span tabindex="0" class="...">Option</span> <span tabindex="0" class="... checked">Option</span> example: checkbox
107. <span tabindex="0" role="checkbox" aria-checked="false" class="...">Option</span> <span tabindex="0" role="checkbox" aria-checked="true" class="... checked">Option</span> •  add role="checkbox" •  make sure it's focusable •  add handling of SPACE •  add aria-checked and dynamically change its value example: checkbox with aria-checked
108. radio button
109. <span tabindex="0" class="...">Yes</span> <span tabindex="0" class="... selected">No</span> <span tabindex="0" class="...">Maybe</span> example: radio button
110. <span tabindex="0" role="radio" aria-checked="false" class="...">Yes</span> <span tabindex="0" role="radio" aria-checked="true" class="... selected">No</span> <span tabindex="0" role="radio" aria-checked="false" class="...">Maybe</span> •  add role="radio" •  add handling of SPACE and cursor keys •  add aria-checked and dynamically change its value •  should be contained inside role="radiogroup" (cfr. <fieldset> ) example: radio button with ARIA (but note incomplete focus handling)
111. disclosure widget
112. <button ...>More details</button> <div class="show" ...> ... </div> example: disclosure widget
113. <button ... aria-expanded="true" aria-controls="disclosure1" >More details</button> <div class="show" ... id="disclosure1"> ... </div> example: disclosure widget with aria-expanded / aria-controls
114. accordion
115. •  ARIA Practices 1.0 suggested using a tab panel pattern (we'll briefly look at this in a moment) •  ARIA Practices 1.1 is more pragmatic: an accordion is seen simply as a series of disclosure widgets (see ARIA Practices 1.1 - 3.1 Accordion)
116. <button ... aria-expanded="true" aria-controls="accordion1" >Item 1</button> <div class="show" ... id="accordion1"> ... </div> <button ... aria-expanded="false" aria-controls="accordion2" >Item 2</button> <div class="show" ... id="accordion2"> ... </div> <button ... aria-expanded="false" aria-controls="accordion3" >Item 3</button> <div class="show" ... id="accordion3"> ... </div> example: accordion using disclosure widgets
117. modal dialog
118. <button>Launch...</button> ... <div ... > <div>My custom dialog</div> ... </div> example: modal dialog ...but focus handling is not really correct...
119. •  when triggered, focus should move to the dialog •  focus should be maintained inside the dialog example: modal dialog with focus management ...but for assistive tech users, it's still not clear what is happening...
120. <button>Launch...</button> ... <div role="dialog" aria-labelledby="dialog-header" aria-describedby="modalDialogDescription" ... > <div id="modalDialogHeader">My custom dialog</div> <div id="modalDialogDescription"> ... </div> ... </div> example: modal dialog with focus management and ARIA ...almost perfect, but assistive tech users can still navigate out of the modal...
121. <div id="wrapper">> <button>Launch...</button> </div> ... <div role="dialog" ...</div> function openModal() { document.getElementById("wrapper").setAttribute("aria-hidden","true" ... } function closeModal() { document.getElementById("wrapper").removeAttribute("aria-hidden"); ... } example: modal dialog with aria-hidden note: aria-hidden does not prevent regular keyboard focus!
122. function openModal() { document.getElementById("wrapper").setAttribute("inert",""); ... } function closeModal() { document.getElementById("wrapper").removeAttribute("inert"); ... } example: modal dialog with inert note: inert does hide elements from accessibility tree and remove behavior such as keyboard focusability. however, not natively supported yet – use the inert polyfill
123. <button>Launch...</button> ... <div role="dialog" aria-modal="true" aria-labelledby="dialog-header" aria-describedby="modalDialogDescription" ... > <div id="modalDialogHeader">My custom dialog</div> <div id="modalDialogDescription"> ... </div> ... </div> example: modal dialog with aria-modal (new in ARIA 1.1) ...but you still need to do the focus management yourself...
124. managing focus
125. complex widgets and focus •  some complex widgets (group of radio buttons, menus, listboxes, tab lists) only have a single "tab stop" •  focus/interactions within the widget are handled programmatically •   TAB / SHIFT + TAB moves to the next widget, not to sub-components
126. keyboard navigation within widgets •  either: "roving" tabindex (only one element inside widget has tabindex="0" , all others tabindex="-1" ) •  or: focus remains on widget itself, denote active child element with aria-activedescendant (and manually scroll into view, provide highlight via CSS) W3C WAI-ARIA 1.1 Authoring Practices - 5.6 Keyboard Navigation Inside Components
127. <span tabindex="-1" role="radio" aria-checked="false" class="...">Yes</span> <span tabindex="0" role="radio" aria-checked="true" class="... selected">No</span> <span tabindex="-1" role="radio" aria-checked="false" class="...">Maybe</span> only one radio button inside the group has focus. changing the selection using CURSOR keys, dynamically changes tabindex , aria- checked and sets focus() on the newly selected radio button example: ARIA Practices 1.1 - Radio Group Using Roving tabindex
128. not all complex widgets lend themselves to "roving" tabindex – e.g. role="combobox" needs aria-activedescendant , as actual focus must remain inside the textbox. example: ARIA Practices 1.1 Combobox with Listbox Popup this approach can be complex, and not always supported by assistive technologies (particularly on mobile).
129. live regions
130. making assistive technology aware of content changes
131. <div id="output"></div> var o = document.getElementById("output"); o.innerHTML = "Surprise!"; // show the notification example: notification as result of button press but how can AT users be made aware of the notification / content change?
132. one way to notify users of assistive technologies of new content (a new element added to the page, made visible, a change in text) is to move focus() programmatically to it <div id="output" tabindex="-1" ></div> var o = document.getElementById("output"); o.innerHTML = "Surprise!"; // show the notification o.focus(); // move focus to the notification but this is not always possible, as it would interrupt the user's current actions... example: notification via focus() and a more problematic example simulating a long-running function.
133. ARIA live regions •  announce a change on content without moving focus to it •   aria-live : off (default), polite , assertive
134. <div id="output" aria-live="polite" ></div> var o = document.getElementById("output"); o.innerHTML = "Surprise!"; // show the notification example: notification via aria-live bonus points: set aria-disabled="true" on the control, and optionally aria-busy="true" on the notification / section of the page that is getting updated. see notification via aria-live , with aria- busy and aria-disabled
135. •  some role s have implicit live region (e.g. role="status" and role="alert" ), as do some markup elements (e.g. <output> )
136. <span role="status" > some form of status bar message... </span> example: status bar <span role="alert" > an alert message (no user interaction) </span> example: alert
137. ARIA live regions need to be "primed" first – the browser and AT need to realize there's a live region, and start watching for changes. •  sending something with role="alert" as part of your static HTML document has no effect – AT won't announce this when the page is loading •  creating a dynamic element with aria-live="..." or an implicit live region role and filling it with content right away will (depending on timing) usually not give browser/AT enough time to "see" the element and notice the change ... again resulting in no announcement
138. // create a new div element var newDiv = document.createElement("div"); // set aria-live property newDiv.setAttribute("aria-live", "polite"); // and give it some content var newContent = document.createTextNode("Surprise!"); // add the text node to the newly created div newDiv.appendChild(newContent); // add the new div to the page document.body.appendChild(newDiv); // ... WON'T ACTUALLY WORK
139. by default, live regions only announce any new/changed content. however, this can be controlled: •   aria-atomic : true / false ("treat the live region as one atomic unit and announce everything") example: live region clock and live region clock with aria-atomic (there's also aria-relevant , but it is badly supported/pointless - see Aaron Leventhal and Rob Dodson: Why authors should avoid aria-relevant).
140. ARIA has many more complex/composite widgets and structures
141. example: tab panels
142. <div role="tablist" ...> <div role="tab" aria-controls="panel1" aria-selected="true" ...>Tab 1</div> <div role="tab" aria-controls="panel2" ...>Tab 2</div> <div role="tab" aria-controls="panel3" ...>Tab 2</div> </div> <div role="tabpanel" id="panel1" aria-hidden="false" >...</div> <div role="tabpanel" id="panel2" aria-hidden="true" >...</div> <div role="tabpanel" id="panel3" aria-hidden="true" >...</div> example: ARIA Practices 1.1 Tabs with Automatic Activation variations on this theme: Marco Zehe - Advanced ARIA tip #1: Tabs in web apps not appropriate if you're just marking up a site navigation...
143. some shortcomings / problems with ARIA
144. as useful as ARIA is, it is far from perfect ... •  some patterns rooted deeply in native (Windows) application paradigms – and as a result, quite limited/restrictive •  straying from these patterns / using ARIA incorrectly can make things worse for users •  certain roles/patterns define specific keyboard interactions – but work badly or not at all in touchscreen + AT scenarios •  particularly for new roles/attributes (ARIA 1.1) and complex patterns, browser and AT support may be lacking
145. example: menu/menubar
146. <div role="menubar" > <div role="menuitem" ...> ... <div role="menu" </div> <div role="menuitem" ...>...</div> <div role="menuitem" ...>...</div> <div role="menuitem" ...>...</div> ... </div> </div> ... </div> example: ARIA Practices 1.1 Navigation Menubar most suitable for real "application-like" web-apps - arguably not appropriate for general "website navigation"
147. ARIA 1.1 menu (role) specific child elements only ( menuitem , menuitemcheckbox , menuitemradio )
148. Using ARIA - 2.15 ARIA Design Patterns and Touch Device Support
149. ARIA Practices 1.1 - Horizontal Slider on Android / Chrome / TalkBack (use volume keys...)
150. ARIA Practices 1.1 - Horizontal Slider on iOS / Safari / VoiceOver (swipe up or down...)
151. ARIA Practices 1.1 - Combobox with Listbox Popup on Android / Chrome / TalkBack
152. ARIA Practices 1.1 - Combobox with Listbox Popup on iOS / Safari / VoiceOver
153. frameworks, web components, angular, etc?
154. •  not everybody codes their complex applications from scratch using hand-made HTML/JavaScript/CSS •  many ready-made libraries, scripts and frameworks offer at least basic ARIA support (by default, or as an "optional" setting or module) •  particularly open source projects offer good opportunities to get involved – file issues, submit pull requests, improve documentation •  lack of accessibility/ARIA support likely not down to malice, but a lack of knowledge or even understanding of the problem...
155. Bootstrap - Accessibility
156. AngularJS Developer Guide - Accessibility with ngAria
157. recap...
158. ARIA is not a magic bullet
159. what ARIA is/isn't ... •  ARIA conveys "what is this thing and what does it do?" to assistive technologies •  ARIA does not influence browser behavior itself – you need to manage keyboard handling, state, etc. yourself •  ARIA is vast and complex, depends on browser/AT support, has shortcomings
160. pragmatic approach to using ARIA •  understand/break-up complex app into simple component elements •  you don't always need ARIA – appropriate HTML usually best •  No ARIA is better than Bad ARIA •  consult ARIA Practices to see if they match an existing pattern •  follow the rules of ARIA •  check main ARIA specification for correct syntax, expected attributes, valid values •  test in actual browser/AT
161. get in touch @patrick_h_lauke github.com/patrickhlauke/aria paciellogroup.com splintered.co.uk