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Re: Is Voiceover more similar to NVDA or JAWS with respect to the accessibility tree?

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From: Murphy, Sean
Date: Jun 3, 2020 4:53PM

Glenn,

What is in the browser accessibility tree is what should be used as the deal breaker. If the name property of the accessibility tree is null, in my mind that is a failure regardless of the screen reader from a WCAG point of view. As aria-label and similar attributes should be populating this property for the assistive technology. This applies to all the different accessibility tree properties of importance such as role, value, etc. The accessibility tree will populate the accessibility API of the OS. In relation to other components like tables, I would still look at the accessibility tree first to make sure it is correctly populated.

Note: The approach which different screen readers handle the information from the accessibility API / Accessibility Tree does vary due to customer demand over the years or their core principles. NVDA is very much following the standards as closely as possible. While Jaws and Voiceover are more interested in the user experiences. Jaws did include a lot of extra support in IE, not sure if this is still the case for Firefox or Chrome. This is my observation of being a screen reader user for the last 30 plus years and working for Freedom scientific. The standard approach for NVDA came from one of the founders when I was speaking to them at a A11y Camp conference in Melbourne.

Sean




Sean Murphy | Digital System specialist (Accessibility)
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From: WebAIM-Forum < <EMAIL REMOVED> > On Behalf Of glen walker
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Subject: [WebAIM] Is VoiceOver more similar to NVDA or JAWS with respect to the accessibility tree?

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Not in functionality or features but in how it interprets the accessibility tree. For example,

First Name <input>

If a label is not associated with an input element, NVDA will not "guess"
at what the label should be. It won't say anything except "edit". Both JAWS and VoiceOver (Mac and iOS) will say "First Name" for the label even though it's not in the accessibility tree.

So for testing purposes, NVDA is more "pure" and can help find a11y bugs.
I've known JAWS has some built in heuristics for fixing bad html but wasn't sure what VoiceOver had built in. With respect to input labels, JAWS and VoiceOver seem to work the same. Are there other heuristics that are similar between the two?

One of the reasons I'm asking is because a customer wants to do all their testing on the Mac. I was trying to convince them that there might be bugs that are missed because VoiceOver is trying to be nice but I wasn't sure how many things VO is nice about. Is there a list of heuristics that both JAWS and VoiceOver have to overcome bad html?