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

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From: Steve Green
Date: Jun 3, 2020 8:54AM

Since the heuristics are a significant piece of intellectual property for an AT vendor, I would be very surprised if any vendor published theirs. That said, I too would be very interested if there are such lists.

I would also make the point (again) that there is a difference between doing a WCAG audit and an accessibility audit. It is not necessary to use any assistive technologies when doing a WCAG audit, and arguably you should not use them. A WCAG audit should be done by inspection of the code and user interface, using tools where they are helpful. The behaviour of assistive technologies is irrelevant and unhelpful.

By contrast, an accessibility audit can be anything you want it to be, and you may well choose to include testing the user experience with one or more screen readers. The choice of operating system, browser and AT should be determined by factors such as your audience and contractual obligations. I would go so far as to say it's unprofessional to test with a particular platform simply because it's what you've got or what you want to use.

Steve Green
Managing Director
Test Partners Ltd


-----Original Message-----
From: WebAIM-Forum < <EMAIL REMOVED> > On Behalf Of glen walker
Sent: 03 June 2020 15:39
To: WebAIM Discussion List < <EMAIL REMOVED> >
Subject: [WebAIM] Is VoiceOver more similar to NVDA or JAWS with respect to the accessibility tree?

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?