Accessibility of HTML5 and Rich Internet Applications - CSUN 2012

Hans Hillen (TPG)

Steve Faulkner (TPG)

02 / 27 / 12 Accessibility of HTML5 and Rich Internet Applications - CSUN 2012 1

 www.paciellogroup.com/training/CSUN2012

 Examples: part 1
http://www.html5accessibility.com/CSUN12/

If you can avoid using:
— JavaScript
— CSS
— ARIA
— HTML5

DO IT!
Now back to reality...

I am not an expert
I know some things about HTML5 and WAI-ARIA
I know some people who know some other things
about HTML5 and WAI-ARIA
I will hold up a virtual sign if you ask a question I cannot
answer
Consider it held up when you ask a question and I look
vague

There’s a clue in the name:
Accessible Rich Internet

Applications

“This specification introduces features to
HTML and the DOM that ease the
authoring of Web-based applications.”

ARIA is not so much about content

ARIA is about interaction

Much of ARIA only makes sense in
conjunction with scripting.

Much of ARIA is about making sense
of scripted interaction

ARIA Stuff that makes sense without
scripting
—Landmark roles

—A few of the relationship attributes

—A few of the document structure roles

ARIA can/could be used with any markup language.
— HTML

— XHTML

— SVG

— MATHML

— MXML

— XUL

Firebug accessibility implemented by Hans Hillen using ARIA

ARIA
attributes

role aria-*

abstract

role

Document
Landmark
widget structure
‘main’
‘heading’

command (abstract role)
composite (abstract role)
input (abstract role)
landmark (abstract role)
range (abstract role)
roletype (abstract role)
section (abstract role)
sectionhead (abstract role)
select (abstract role)
structure (abstract role)
widget (abstract role)
window (abstract role)

Don’t use

widget

Simple Composite
‘button’ ‘menubar’
typically act as containers that
manage other, contained
widgets.

What do they do?
How do they do it?
What they don’t do
(generally)

Override native html roles If you want the native semantic to
be used Do not add a role!
BAD
<h1 role=“button”>heading text</h1>

GOOD
<h1>
<span role=“button”>heading text</span>
</h1>

Expose role information to accessibility APIs

role=“button”

UIA
MAC
WAI- IAccessible2 Control
MSAA role ATK role Accessibi
ARIA role role Pattern
lity Role
Type
ROLE_SYSTEM
IA2_ROLE_TOG ATK_ROLE_PUS
button _PUSHBUTTON
GLE_BUTTON
Button
H_BUTTON
AXButton
.
HTML to Platform Accessibility APIs Implementation Guide

role=“button”

“to activate press space bar”
http://www.paciellogroup.com/blog/aria-tests/user-input-widgets.html
demo

They are not magic!
They do not (generally) add ANY interaction
behaviours.
Adding a role does not:

Make an element focusable

Provide keyboard events

Add properties
Button example

The following roles are regions of the page
intended as navigational landmarks.

application form html4
banner main
complementary html5 navigation html5
contentinfo search

demo

aria-*

Widget Live Region Drag & Drop Relationship
‘aria-checked’ ‘aria-live’ ‘ aria-dragged’ ‘aria-labelledby’

— Use of ARIA in HTML<5 is non conforming and
probably always will be.
— It doesn’t make any difference

— Simple solution – use the HTML5 doctype

<!DOCTYPE html>

There are rules:
HTML5 – WAI-ARIA 3.2.7

You can use:

—validator.w3.org/nu/

But some of the rules are out of date

• Browsers with ARIA support: rough guide
– Firefox 3+
– Internet Explorer 8+
– Safari 5 (Mac/iOS)
– Chrome 17

• Assistive Technology:
– JAWS 8 and up
– WindowEyes 5.5 and up
– Zoomtext
– Free screen readers: NVDA, ORCA
– VoiceOver
– ChromeVox

• Libraries (support)
– ExtJs, Jquery, Dojo, GWT, YUI, Glow + others

Chart Title
10 JAWS 13 NVDA 2012
9 VoiceOver
8
Support score

7 Orca
6
5 Window eyes
4 7.5
3
2
1
0
1

 Accessibility support: www.HTML5accessibility.com

 New interactive elements:
html5 interactive controls
 Text alternatives: long descriptions

 Canvas: canvas example

 Structural elements: HTML5 structural elements

 Figure and figcaption: figures and figcaption

 Aviewer (free desktop application for windows )
 Dom Inspector (free Firefox extension)
 Inspect.exe (free desktop application for windows
available as part of the Windows SDK)
 Accprobe (free open source cross platform app)
 Accessibility Inspector (free Mac app)
 Java ferret (free cross platform app)
 Accerciser (free gnome desktop app)

 www.twitter.com/stevefaulkner

 www.twitter.com/hanshillen

 www.paciellogroup.com/blog

 www.html5accessibility.com

 sfaulkner@paciellogroup.com

 hhillen@paciellogroup.com

Hans Hillen (TPG)

Steve Faulkner (TPG)


 Keyboard and Focus Management

 Labeling and Describing

 Live Regions

 Form Validation

 Mode Conflicts

 Fallback Solutions


Problem:
 Images, divs, spans etc. are not standard controls with
defined behaviors
o Not focusable with keyboard
o Have a default tab order
o Behavior is unknown
Solution:
 Ideally: Use native focusable HTML controls
o <a>, <input type=“image” />, <button>, etc.
 Or manually define keyboard focus and behavior needs


 Reachability: Moving keyboard focus to a widget
o Through tab order
• Native focusable controls or tabindex=“0”
o Through globally defined shortcut
o By activating another widget
 Operability: Interacting with a widget
o All functionally should be performable through keyboard
and mouse input


 To be accessible, ARIA input widgets need focus
o Use natively focusable elements, such as <a>, <input />, etc
o 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)
o 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:
o 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


 Every widget needs to be operable by keyboard.
common keystrokes are:
o Arrow keys
o Home, end, page up, page down
o Enter, space
o ESC
 Mimic the navigate in the desktop environment
o DHML Style Guide: http://dev.aol.com/dhtml_style_guide
o ARIA Best Practices: http://www.w3.org/TR/wai-aria-practices/

 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
o But keyboard users still need to be able to skip
 Other alternatives for skipping:
o Collapsible sections
o Consistent shortcuts (e.g. a shortcut that moves focus between
panes and dialogs)
o Custom focus manager that allows the user to move focus into
a container to skip its contents


 More and more web apps use HTML based popup dialogs rather than actual
browser windows/dialogs
o Get a screen reader to perceive it properly using role="dialog"

 Dialogs should have their own tab order
o Focus should "wrap"

 For modal dialogs, it should not be possible to interact with the main page
o Prevent keyboard access
o 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
o Focus should be placed back on a logical element, e.g. the button that triggered the dialog.


 Trees, Lists, Grids can support single or multiple
selection
o 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


 All of these must have an accessible name:
o Every interactive widget
o Composite widgets (menu(bar), toolbar, tablist, tree, grid)
o Groups, regions and landmarks
 Browsers determines an element’s accessible name by checking the
following :
1. aria-labelledby
2. aria-label
3. Associated label (<label for=“myControl”>) or alt attribute
4. Text contents
5. Title attribute

Optionally, add an accessible description for additional info


 Aria-labelledby=“elemID”
o Points to element ID that identifies the widget.
o Can also use regular label element / title attribute
 Aria-describedby=“elemID”
o Optional, provides additional info besides identity
o Useful for additional info, instructions, hints
 Aria-label=“text”
o Only use when no on-screen text
 Title attribute will also work

<h2 id=“treeLbl”>My Folders</h2>
<p id=“treeDesc” class=“hidden”>Each tree item has a context menu with more options</p>
<div role=“tree” aria-labelledby=“treeLbl” aria-describedby=“treeDesc”>


 Aria-labelledby=“IDREFS”
o Value is one or more IDs of elements that identifiy the widget.
o The elements ‘aria-labelledby’ targets can be any kind of text based element, anywhere
in the document.
o Add multiple Ids to concatinate label text:
• Multiple elements can label one widget, and one element can label multiple widgets. (example)
 Aria-describedby=“IDREFS”
o Similar to labelledby, except used for additional description, e.g. Form
hints, instructions, etc.
 Aria-label
o Simply takes a string to be used as label.
o Quick and dirty way of making the screen reader say what you want.
o 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”>
...


 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>


 Problem: content is updated dynamically on screen may not be apparent to screen reader users
o No page refresh, no screen reader announcement
o Change is only announced by stealing focus
o Users miss relevant information
o Users have to ‘search’ for updated page content

 Solution: live regions indicate page updates without losing focus
o Screen readers announce change based on type of live region

 Challenge: When should users be informed of the change?
o Ignore trivial changes: changing seconds in a clock
o Announce important changes immediately / as convenient


 Role=“alert” for one-time, high-priority notifications
o Shown for a period of time, or until the cause of the alert is solved
o Basic message, no complex content
o 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.
o May contain other widgets, such as buttons or other form fields
o 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


1. Identify which part (containing HTML element) is expected to be updated
2. To make it live, add ‘aria-live’ attribute with a politeness value:
o Off (default): Do not speak this region
o Polite: Speak this region when the user is idle
o Assertive: Speak this region as soon as possible

3. Choose whether entire region should be announced or just the part that
changed:
o ‘aria-atomic': true (all) or false (part)

4. Add other attributes as necessary:
o aria-relevant: choose what to announce:
• Combination of ‘Additions’, ‘removals’, ‘text’, ‘all’
o aria-busy: indicate content is still updating
o aria-labelledby, aria-describedby: label and describe regions


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


 Screen readers normally browse in ‘virtual mode’
o Navigates a virtual copy of the web page
o 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
o Interactive widgets need to define the keystrokes themselves
o Content needs to be live, not a virtual copy
o Automatically switches between virtual and non-virtual mode
 role=“application”
o Screen reader switches to non-virtual for these elements
o Must provide all keyboard navigation when in role=“application” mode
o Screen readers don’t intercept keystrokes then, so typical functions will not work


 For apps with ‘reading’ or ‘editing’ sections
o A reading pane in an email client
o Screen reader switches back to virtual mode, standard
‘web page reading’ shortcuts work again
o 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.


 Role=“presentation” overrides existing role
o Useful to ‘hide’ default HTML roles from AT
 For example:
o Hide layout tables by adding the role to the <table>
element
o Textual content read by the screen reader but table is ignored


 In IE, 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
o Hide fieldset's padding, margin, and border
o Move legend off-screen

<fieldset role="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>


 Developers often use links as (icon) buttons
o Side effect: screen reader will announce them as a link, not a button
 This can be made accessible by setting role="button"
o 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
o 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>


 Three types of hiding:
1. Hiding content visually and from AT:
2. Hiding content visually, but not from AT
3. Hiding content from AT, but not visually


 Display: none;
o Hides content both visually and from AT products
o Only works when CSS is supported (by user agent, user, or
AT product)
o Only use to hide content that still ‘makes sense’
• E.g. contents of a collapsible section
o 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


 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
o 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);
}


 Sometimes developers want to hide content from screen
readers, e.g.:
o Duplicate controls
o Redundant information that was already provided through semantic
markup.

 Difficult to achieve:
o Role=“presentation” will remove native role, but content is still visible
for AT products
o Aria-hidden=“true” would be ideal, but:
• The spec did not intend for aria-hidden to be used this way
• 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)


 Some developers will use multiple HTML <table>
elements to create one single grid. For example:
o One <table> for the header row, one <table> for the body rows
o 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
o Association between column headers and cells is broken
o Screen reader's table navigation is broken


 If using a single table is not feasible, use ARIA to fix
the grid structure as perceived by the screen reader
o Use role="presentation" to hide the original table
elements form the screen readers
o Use a combination of
"grid", "row", "gridcell", "columnheader" roles to make the
screen reader see one big grid.


 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>


 Questions?

 Additional Topics?

 Course Material:
http://www.paciellogroup.com/training/CSUN2012


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