Accessibility of HTML5 and Rich Internet Applications (Part 2)

1. Hans Hillen (TPG) Steve Faulkner (TPG) Accessibility of HTML5 and Rich Internet Applications (Part 2) Accessibility of HTML5 and Rich Internet Applications - CSUN 2013

2. In This Part: • Keyboard and Focus Management • Labeling and Describing • Live Regions • Form Validation • Mode Conflicts • Fallback Solutions Accessibility of HTML5 and Rich Internet Applications - CSUN 2013

3. Keyboard and Focus Management Accessibility of HTML5 and Rich Internet Applications - CSUN 2013

4. The Problem with Custom Controls Problem: • Images, divs, spans etc. are not standard controls with defined behaviors • Not focusable with keyboard • Have a default tab order • Behavior is unknown Solution: • Ideally: Use native focusable HTML controls • <a>, <input type=“image” />, <button>, etc. • Or manually define keyboard focus and behavior needs Accessibility of HTML5 and Rich Internet Applications - CSUN 2013

5. Keyboard Issues in a Nutshell • Reachability: Moving keyboard focus to a widget • Through tab order • Native focusable controls or tabindex=“0” • Through globally defined shortcut • By activating another widget • Operability: Interacting with a widget • All functionally should be performable through keyboard and mouse input Accessibility of HTML5 and Rich Internet Applications - CSUN 2013

6. Focus & Keyboard Accessibility • To be accessible, ARIA input widgets need focus • Use natively focusable elements, such as <a>, <input />, etc • Add ‘tabindex’ attribute for non focusable elements, such as <span>, <div>, etc. • Tabindex=“0”: Element becomes part of the tab order • Tabindex=“-1” (Element is not in tab order, but focusable) • For composite widgets (menus, trees, grids, etc.): • Every widget should only have 1 stop in the tab order. • Keep track where your widget’s current tab stop is: • Alternative for tabindex: ‘aria-activedescendant=“<idref>” • Focus remains on outer container • AT perceives element with the specified ID as being focused. • You must manually highlight this active element, e.g. With CSS Accessibility of HTML5 and Rich Internet Applications - CSUN 2013

7. Keyboard Handling • Every widget needs to be operable by keyboard. common keystrokes are: • Arrow keys • Home, end, page up, page down • Enter, space • ESC • Mimic the navigate in the desktop environment • DHML Style Guide: http://dev.aol.com/dhtml_style_guide • ARIA Best Practices: http://www.w3.org/WAI/PF/aria-practices/ Accessibility of HTML5 and Rich Internet Applications - CSUN 2013

8. Skipping Mechanisms • The ability to skip content is crucial for both screen reader and keyboard users • Skip links are out of date, out of fashion and often misused • But keyboard users still need to be able to skip • Other alternatives for skipping: • Collapsible sections • Consistent shortcuts (e.g. a shortcut that moves focus between panes and dialogs) • Custom focus manager that allows the user to move focus into a container to skip its contents Accessibility of HTML5 and Rich Internet Applications - CSUN 2013

9. Popup Dialogs and Windows • More and more web apps use HTML based popup dialogs rather than actual browser windows/dialogs • Get a screen reader to perceive it properly using role="dialog" • Dialogs should have their own tab order • Focus should "wrap" • For modal dialogs, it should not be possible to interact with the main page • Prevent keyboard access • Virtual mode access can't be prevented • For non modal dialogs, provide shortcut to switch between dialog and main page • If dialog supports moving or resizing, these features must be keyboard accessible • Support closing dialogs using Enter (OK) or Escape (Cancel) keys • Focus should be placed back on a logical element, e.g. the button that triggered the dialog. Accessibility of HTML5 and Rich Internet Applications - CSUN 2013

10. Selection & Editing • Trees, Lists, Grids can support single or multiple selection • Multiple selection must be keyboard accessible, for example: • Shift + arrow keys: contiguous selection • Ctrl + arrow keys: move focus without selection • Ctrl + space: Toggle focused item in selection (discontiguous selection) • Editable grids need to support switching to edit mode by keyboard Accessibility of HTML5 and Rich Internet Applications - CSUN 2013

11. Labeling and Describing Accessibility of HTML5 and Rich Internet Applications - CSUN 2013

12. Labeling in a Nutshell • All of these must have an accessible name: • Every interactive widget • Composite widgets (menu(bar), toolbar, tablist, tree, grid) • Groups, regions and landmarks • Browsers determines an element’s accessible name by checking the following : • aria-labelledby • aria-label • Associated label (<label for=“myControl”>) or alt attribute • Text contents • Title attribute Optionally, add an accessible description for additional info Accessibility of HTML5 and Rich Internet Applications - CSUN 2013

13. Labeling And Describing Widgets (2) • Aria-labelledby=“IDREFS” • Value is one or more IDs of elements that identifiy the widget. • The elements ‘aria-labelledby’ targets can be any kind of text based element, anywhere in the document. • Add multiple Ids to concatinate label text: • Multiple elements can label one widget, and one element can label multiple widgets. (example) • Aria-describedby=“IDREFS” • Similar to labelledby, except used for additional description, e.g. Form hints, instructions, etc. • Aria-label • Simply takes a string to be used as label. • Quick and dirty way of making the screen reader say what you want. • Very easy to use, but only supported in Firefox at the moment. <h2 id=“treeLbl”>My Folders</h2> <p class=“hidden”>Each tree item has a context menu with more options</p> <div role=“tree” aria-labelledby=“treeLbl” aria-describedby=“treeDesc”> ... Accessibility of HTML5 and Rich Internet Applications - CSUN 2013

14. Labeling containers • Containers such as toolbars, dialogs, and regions provide context for their contents • When the user moves focus into the container, the screen reader should first announce the container before announcing the focused control <div role="dialog" aria-labelledby="dialogTitle" aria-describedby="dialogDescription"> <h2 id="dialogTitle">Confirm</h2> <p id="dialogDescription"> Are you sure you want to do that? </p> <button>Yes</button> <button>No</button> </div> Accessibility of HTML5 and Rich Internet Applications - CSUN 2013

15. Labeling Tables • <caption> still alive and kicking • In HTML5 it’s allowed to nest headings • Summary attribute obsolete in HTML5 <table> <caption> <h2>Animals</h2> </caption> <tbody> <tr> <th scope="col" abbr="pet name">Name <th scope="col">Age</th> <th scope="col">Species</th> </tr> ... </tbody> </table> Accessibility of HTML5 and Rich Internet Applications - CSUN 2013

16. Live Regions Accessibility of HTML5 and Rich Internet Applications - CSUN 2013

17. ARIA Live Regions • Problem: content is updated dynamically on screen may not be apparent to screen reader users • No page refresh, no screen reader announcement • Change is only announced by stealing focus • Users miss relevant information • Users have to ‘search’ for updated page content • Solution: live regions indicate page updates without losing focus • Screen readers announce changebased on type of live region • Challenge: When should users be informed of the change? • Ignore trivial changes: changing seconds in a clock • Announce important changes immediately / as convenient Accessibility of HTML5 and Rich Internet Applications - CSUN 2013

18. “Built In” Live Regions • Role=“alert” for one-time, high-priority notifications • Shown for a period of time, or until the cause of the alert is solved • Basic message, no complex content • The element with the alert role does not need to be focused to be announced • Role=“alertdialog” is similar to alert, but for actual (DHTML) dialogs. • May contain other widgets, such as buttons or other form fields • Does require a sub-element (such as a ‘confirm’ button) to receive focus • Live regions ‘built into ‘ roles’ • role="timer", "log", "marquee" or "status“ get default live behavior • Role=“alert” implicitly sets live to assertive Accessibility of HTML5 and Rich Internet Applications - CSUN 2013

19. How to Use Live Regions • Identify which part (containing HTML element) is expected to be updated • To make it live, add ‘aria-live’ attribute with a politeness value: • Off (default): Do not speak this region • Polite: Speak this region when the user is idle • Assertive: Speak this region as soon as possible • Choose whether entire region should be announced or just the part that changed: • ‘aria-atomic': true (all) or false (part) • Add other attributes as necessary: • aria-relevant: choose what to announce: • Combination of ‘Additions’, ‘removals’, ‘text’, ‘all’ • aria-busy: indicate content is still updating • aria-labelledby, aria-describedby: label and describe regions Accessibility of HTML5 and Rich Internet Applications - CSUN 2013

20. Forms & Validation Accessibility of HTML5 and Rich Internet Applications - CSUN 2013

21. Forms & ARIA • You can used ARIA to make your form validation easier to manage. • aria-required & aria-invalid states • Role="alert" to flag validation errors immediately • Use validation summaries invalid entries easier to find • Use role=“group” or Role="alertdialog" to mark up the summary • Link to corresponding invalid controls from summary items • Use different scope levels if necessary • Visual tooltips: Useful for validation messages and formatting instructions • Tooltips must be keyboard accessible • Tooltip text must be associated with the form control using aria-describedby • Live Regions: Use for concise feedback messages Accessibility of HTML5 and Rich Internet Applications - CSUN 2013

22. Mode Conflicts Accessibility of HTML5 and Rich Internet Applications - CSUN 2013

23. Role = Application • Screen readers normally browse in ‘virtual mode’ • Navigates a virtual copy of the web page • Intercepts all keystrokes for its own navigation (e.g. ‘H’ for heading navigation) • For dynamic Web apps, virtual mode may need to be turned off • Interactive widgets need to define the keystrokes themselves • Content needs to be live, not a virtual copy • Automatically switches between virtual and non-virtual mode • role=“application” • Screen reader switches to non-virtual for these elements • Must provide all keyboard navigation when in role=“application” mode • Screen readers don’t intercept keystrokes then, so typical functions will not work Accessibility of HTML5 and Rich Internet Applications - CSUN 2013

24. Role = Document • For apps with ‘reading’ or ‘editing’ sections • A reading pane in an email client • Screen reader switches back to virtual mode, standard ‘web page reading’ shortcuts work again • Read / edit documents in a web application • Banner, complementary, contentinfo, main, navigation, search & form • When applied to a container inside an application role, the screen reader switches to virtual mode. Accessibility of HTML5 and Rich Internet Applications - CSUN 2013

25. Fall Back Solutions Accessibility of HTML5 and Rich Internet Applications - CSUN 2013

26. Role = Presentation • Role=“presentation” overrides existing role • Useful to ‘hide’ default HTML roles from AT • For example: • Hide layout tables by adding the role to the <table> element • Textual content read by the screen reader but table is ignored Accessibility of HTML5 and Rich Internet Applications - CSUN 2013

27. Fall back solution for dialogs • In IE, some versions of JAWS currently does not properly announce dialogs when moving focus into them • It's possible to provide a fallback solution for IE to fix this, using hidden fieldsets to apply the ARIA dialog markup to • Hide fieldset's padding, margin, and border • Move legend off-screen <fieldsetrole="dialog" aria-labelledby="dialogTitle" aria-describedby="dialogDescription"> <legend id="dialogTitle">Confirm</legend> <p id="dialogDescription"> Are you sure you want to do that? </p> <button>Yes</button> <button>No</button> </fieldset> Accessibility of HTML5 and Rich Internet Applications - CSUN 2013

28. Fallback solutions for link buttons • Developers often use links as (icon) buttons • Side effect: screen reader will announce them as a link, not a button • This can be made accessible by setting role="button" • Screen reader announces link as button now, but also provides hint for using a button ("press" space to activate) • You lie! Links work through the Enter key, Space will scroll down the page • To make sure JAWS is not lying, you'll have to manually add a key event handler for the Space key. <a role="button" onkeypress="handleKeyPress(event);">refresh</a> Accessibility of HTML5 and Rich Internet Applications - CSUN 2013

29. Hiding Content • Three types of hiding: • Hiding content visually and from AT: • Hiding content visually, but not from AT • Hiding content from AT, but not visually Accessibility of HTML5 and Rich Internet Applications - CSUN 2013

30. 1. Hiding Content from All • Display: none; • Hides content both visually and from AT products • Only works when CSS is supported (by user agent, user, or AT product) • Only use to hide content that still ‘makes sense’ • E.g. contents of a collapsible section • Do not use for content that provides incorrect information • E.g. preloaded error messages that are not applicable at the moment, or stale content • Instead, this content should be removed from the DOM completely Accessibility of HTML5 and Rich Internet Applications - CSUN 2013

31. 2. Hiding Content Visually • Hiding content off-screen will still make it available for screen readers, without it being visible • Useful to provide extra information to screen reader users or users that do not support CSS • E.g. add hidden headings, screen reader instructions, role & state info for older technology /* Old */ .offscreen { position: absolute; left: -999em; } /* New */ .ui-helper-hidden-accessible { position: absolute !important; clip: rect(1px 1px 1px 1px); clip: rect(1px,1px,1px,1px); } Accessibility of HTML5 and Rich Internet Applications - CSUN 2013

32. 3. Hiding Content From AT Only • Sometimes developers want to hide content from screen readers, e.g.: • Duplicate controls • Redundant information that was already provided through semantic markup. • Difficult to achieve: • Role=“presentation” will remove native role, but content is still visible for AT products • Aria-hidden=“true” would be ideal, but: • Browsers handle aria-hidden differently • IE does nothing • FF exposes content but marks it as hidden • Chrome does not expose content (i.e. truly hides it) Accessibility of HTML5 and Rich Internet Applications - CSUN 2013

33. ARIA-HIDDEN • JAWS 14 and NVDA will honor aria-hidden in IE, Firefox and Chrome • regardless of whether the browsers actually expose it! • VoiceOver does not honor aria-hidden at this point <a href="#"> <span aria-hidden="true">A</span> <span class="HiddenText">Small Font</span> </a> Accessibility of HTML5 and Rich Internet Applications - CSUN 2013

34. Grids and Tables Accessibility of HTML5 and Rich Internet Applications - CSUN 2013

35. Fixing Incorrect Grid Structure (1) • Some developers will use multiple HTML <table> elements to create one single grid. For example: • One <table> for the header row, one <table> for the body rows • One <table> for every single row • Why? Because this is easier to manage, style, position, drag & drop, etc. • Screen reader does not perceive one single table, but it sees two ore more separate tables • Association between column headers and cells is broken • Screen reader's table navigation is broken Accessibility of HTML5 and Rich Internet Applications - CSUN 2013

36. Fixing Incorrect Grid Structure (2) • If using a single table is not feasible, use ARIA to fix the grid structure as perceived by the screen reader • Use role="presentation" to hide the original table elements form the screen readers • Use a combination of "grid", "row", "gridcell", "columnheader" roles to make the screen reader see one big grid. Accessibility of HTML5 and Rich Internet Applications - CSUN 2013

37. Fixing Incorrect Grid Structure (3) • Using ARIA to create a correct grid structure <div role="grid"> <table role="presentation"> <tr role="row"> <th role="columnheader">Dog Names</th> <th role="columnheader">Cat Names</th> <th role="columnheader">Cow names</th> </tr> </table> <table role="presentation"> <tr role="row"> <td role="gridcell">Fido</td> <td role="gridcell">Whiskers</td> <td role="gridcell">Clarabella</td> </tr> </table> </div> Accessibility of HTML5 and Rich Internet Applications - CSUN 2013

38. Anything Else? • Questions? • Additional Topics? • Course Material: http://www.paciellogroup.com/training/CSUN2013 Accessibility of HTML5 and Rich Internet Applications - CSUN 2013