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Most modern front-end builds contain bits of hidden content. Some have large parts of the application hidden from view. In this talk, I’ll discuss various ways of making things invisible, and explain what their impact on an application’s accessibility could be.

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Hiding
content Hidde de Vries / @hdv / Fronteers Jam Session, Amsterdam / 05-10-2017

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My name is Hidde

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My name is Hidde

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Hiding
content

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This is actually an accessibility talk

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Tactile paving

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Elevator

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Colour

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Language

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Code

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When you send your
markup to the browser, it generates two trees (amongst others)

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DOM tree

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Accessibility tree

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Roles role = alert role = link role = button role = checkbox role = tab role = radio role = dialog role = progressbar role = slider role = tooltip

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States hidden open expanded checked pressed selected hidden open expanded checked

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Labels “skip to content” “open menu” “first name” “table of contents” “about us” “show more” “click here” “go to next photo” “skip to content” “open menu”

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People use AT, assistive technologies. Examples: braille terminals, screenreaders speech input software, alternate input devices

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Accessibility tree Platform APIs AT Microsoft Active Accessibility Microsoft User Interface Automation

MSAA

Mac OS X Accessibility Protocol

Linux/Unix Accessibility Toolkit

IAccessible2 braille text-to-speech screen magnifiers alternate pointing devices

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Accessibility tree Platform APIs AT Microsoft Active Accessibility Microsoft User Interface Automation

MSAA

Mac OS X Accessibility Protocol

Linux/Unix Accessibility Toolkit

IAccessible2 Yo u r markup DOM tree

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Hiding
content

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Hiding from screen “visually hidden”

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Icon button EXAMPLE Please accept our cookie policy OK ×

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Required indicator EXAMPLE First name *

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position: absolute; left: -9999em;

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Hiding from AT

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A decorative icon EXAMPLE ! Cars

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Repeating text that hinders AT users EXAMPLE Our company won a prize We are very proud to announce that we were nominated for an amazing price and that we have actually won it, too. Read more We opened a new office With the great opening party that took place yesterday, it is now official: our
new office in Utrecht is open! Read more We’ll be at the trade show The trade show is taking place next week and we will be presenting interesting new stuff. Visit our booth! Read more

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Repeating text that hinders AT users EXAMPLE Our company won a prize We are very proud to announce that we were nominated for an amazing price and that we have actually won it, too. Read more We opened a new office With the great opening party that took place yesterday, it is now official: our
new office in Utrecht is open! Read more We’ll be at the trade show The trade show is taking place next week and we will be presenting interesting new stuff. Visit our booth! Read more Read more Read more Read more

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aria-hidden

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If you find you have to use aria-hidden , this may indicate there’s something wrong with the page

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Repeating text that hinders AT users EXAMPLE Our company won a prize We are very proud to announce that we were nominated for an amazing price and that we have actually won it, too. Read more We opened a new office With the great opening party that took place yesterday, it is now official: our
new office in Utrecht is open! Read more We’ll be at the trade show The trade show is taking place next week and we will be presenting interesting new stuff. Visit our booth! Read more

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Hiding from everything

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A modal panel that is not currently shown EXAMPLE Perhaps the most heavily-repeated pattern in JavaScript-based page manipulation is showing and hiding content. Tabbed interfaces. Collapsible elements. Accordion widgets. It crops up nearly everywhere. In and of itself, this pattern is not a bad thing, but few people realize how profoundly your choice of hiding mechanism can influence the accessibility of your content to assistive technologies like screen readers. When building custom JavaScript-based widgets, it’s quite easy to fully control the hiding mechanism, but when you begin working with animation libraries like jQuery or Scriptaculous, the hiding mechanism is typically dictated by the library, leaving you little control over the accessibility of your Are you sure? NO YES

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A tab control that   is closed EXAMPLE

1. Personal details

2. Your application

3. Agreement

4. Summary △

▽

▽

▽

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display: none;

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hidden

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Not exposed by a11y tree Not rendered Invisible to text search

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Inert

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inert https://github.com/WICG/inert https://html.spec.whatwg.org/multipage/interaction.html#inert

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Makes the element and its entire subtree inert :
visible, but unusable

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No pointer events. No focus. Invisible to text search. Impossible to select.

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Rest of the page while modal is open (“<dialog> without <dialog>” – Hixie ) EXAMPLE Perhaps the most heavily-repeated pattern in JavaScript-based page manipulation is showing and hiding content. Tabbed interfaces. Collapsible elements. Accordion widgets. It crops up nearly everywhere. In and of itself, this pattern is not a bad thing, but few people realize how profoundly your choice of hiding mechanism can influence the accessibility of your content to assistive technologies like screen readers. When building custom JavaScript-based widgets, it’s quite easy to fully control the hiding mechanism, but when you begin working with animation libraries like jQuery or Scriptaculous, the hiding mechanism is typically dictated by the library, leaving you little control over the accessibility of your Are you sure? NO YES

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Non current
carousel items EXAMPLE Now playing ➜ ➜

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‘Shipping address’ section when ‘Same as billing address’ is checked EXAMPLE Billing address Shipping address ✔ Same as billing address Street
* Postal code
* City
*

Street *

Postal code *

City *

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Hiding content From screen From AT From everything Inert Accessible to:
✔ AT users

✗ sighted users Accessible to:
✗ AT users

✔ sighted users Accessible to:
✗ AT users

✗ sighted users Visible, but not usable

Note that there are a lot of different ATs, and they are not all for users with sight impairments

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Further reading http://www.scottohara.me/blog/2017/04/14/inclusively-hidden.html

https://github.com/alice/inert

https://allyjs.io/tutorials/hiding-elements.html

https://hiddedevries.nl/en/blog/2017-04-11-on-hiding-content

https://www.w3.org/TR/html-aam-1.0/

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Thanks for listening.

Tweet/email any questions/comments! @hdv / hidde@hiddedevries.nl