Hans Hillen (TPG) Steve Faulkner (TPG) 02 / 25 / 13 Accessibility of HTML5 and Rich Internet...

Accessibility of HTML5 and Rich Internet Applications (Part 2)

Hans Hillen (TPG)

Steve Faulkner (TPG)

02 / 25 / 13 Accessibility of HTML5 and Rich Internet Applications - CSUN 2013 1

In This Part:

Keyboard and Focus Management

Labeling and Describing

Live Regions

Form Validation

Mode Conflicts

Fallback Solutions


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 behaviorso 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

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Keyboard Issues in a Nutshell 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 widgeto All functionally should be performable through

keyboard and mouse input


Focus & Keyboard Accessibility 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



Keyboard Handling

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 environmento DHML Style Guide: http://

dev.aol.com/dhtml_style_guide

o ARIA Best Practices: http://www.w3.org/WAI/PF/aria-practices/

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http://dev.aol.com/dhtml_style_guide

http://dev.aol.com/dhtml_style_guide

http://www.w3.org/WAI/PF/aria-practices/

http://www.w3.org/WAI/PF/aria-practices/

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 misusedo 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


Popup Dialogs and Windows More and more web apps use HTML based popup dialogs rather than actual

browser windows/dialogso Get a screen reader to perceive it properly using role="dialog"

Dialogs should have their own tab ordero 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) keyso Focus should be placed back on a logical element, e.g. the button that triggered the

dialog.


Selection & Editing

Trees, Lists, Grids can support single or multiple selectionoMultiple 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


Labeling and Describing


Labeling in a Nutshell

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 info02 / 25 / 13 Accessibility of HTML5 and Rich Internet Applications - CSUN 2013 12

Labeling And Describing Widgets (2) 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-labelo 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”>...02 / 25 / 13 Accessibility of HTML5 and Rich Internet Applications - CSUN 2013 13

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>


Labeling Tables

<caption> still alive and kickingo 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>


Live Regions



ARIA Live Regions

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

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“Built In” Live Regions

Role=“alert” for one-time, high-priority notificationso 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

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How to Use Live Regions

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

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Forms & Validation


Forms & ARIA

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 findo 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 instructionso 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


Mode Conflicts



Role = Application

Screen readers normally browse in ‘virtual mode’o Navigates a virtual copy of the web pageo Intercepts all keystrokes for its own navigation (e.g. ‘H’ for heading

navigation)

For dynamic Web apps, virtual mode may need to be turned offo Interactive widgets need to define the keystrokes themselveso Content needs to be live, not a virtual copyo Automatically switches between virtual and non-virtual mode

role=“application”o Screen reader switches to non-virtual for these elementso Must provide all keyboard navigation when in role=“application”

modeo Screen readers don’t intercept keystrokes then, so typical functions will

not work02 / 25 / 13


Role = Document

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.

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Fall Back Solutions



Role = Presentation

Role=“presentation” overrides existing roleo 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

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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 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>


Fallback solutions for link buttons

Developers often use links as (icon) buttonso 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>


Hiding Content

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


1. Hiding Content from All Display: none;

o Hides content both visually and from AT products

oOnly works when CSS is supported (by user agent, user, or AT product)

oOnly 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


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 CSSo 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);

}


3. Hiding Content From AT Only 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:• 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)


ARIA-HIDDEN

<a href="#"> <span aria-hidden="true">A</span> <span class="HiddenText">Small Font</span></a>


JAWS 14 and NVDA will honor aria-hidden in IE, Firefox and Chromeo regardless of whether the browsers actually

expose it!

VoiceOver does not honor aria-hidden at this point

Grids and Tables


Fixing Incorrect Grid Structure (1)

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 tableso 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>


Anything Else?

Questions?

Additional Topics?

Course Material: http://www.paciellogroup.com/training/CSUN2013


http://www.paciellogroup.com/training/CSUN2013

http://www.paciellogroup.com/training/CSUN2013

Hans Hillen (TPG) Steve Faulkner (TPG) 02 / 25 / 13 Accessibility of HTML5 and Rich Internet...

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