About Accessibility Events

Accessibility Events is an experimental web development feature available on macOS 10.14 and later and iOS 12 and later, which requires the Accessibility Object Model feature to be turned on in advanced settings in Safari.

How Accessibility Events are used

The new Accessibility Events feature provides a way for web developers to ensure that their custom controls, such as custom web sliders, are accessible by users of assistive technology. These actions can now be triggered through assistive technologies like VoiceOver and Switch Control, or through mainstream input devices like keyboards. Accessibility Events is a subfeature of the Accessibility Object Model (AOM) project, an emerging web technology currently under development as a joint W3C effort by Apple, Google, and the Mozilla Foundation. The AOM is turned off by default in iOS and macOS.

Turn on Accessibility Events

While the Accessibility Events control is on by default, the feature only functions when the AOM setting is enabled, which is a developer feature that is off by default.

To turn on Accessibility Events on your Mac:

  1. Choose Safari > Preferences.
  2. Click Advanced, then select Show Develop Menu in menu bar.
  3. From the Safari menu bar, choose Develop > Experimental Features > Accessibility Object Model.
  4. Make sure that Accessibility Events is turned on in  > System Preferences > Accessibility >  VoiceOver > Open VoiceOver Utility > Web > General > Accessibility Events.

On Mac, Switch Control observes the Accessibility Events setting in VoiceOver Utility.

To turn on Accessibility Events on your iPhone, iPad, or iPod touch:

  1. Go to Settings > Safari > Advanced > Experimental Features.
  2. Tap to turn on Accessibility Object Model.
  3. Tap Settings > General > Accessibility to make sure that Accessibility Events is turned on for VoiceOver and Switch Control. For VoiceOver, tap VoiceOver > Web > Accessibility Events. Or for Switch Control, tap Switch Control > Web > Accessibility Events.


Apple is committed to accessibility and privacy. The Accessibility Events feature does not allow websites to specifically query whether individuals are using a screen reader or other specific assistive technology, nor does it provide information about a user's ability or disability. However, web developers might be aware that assistive technology is active on a device, in order to deliver a website that is compatible with the assistive technology.

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