Does Jaws (and other screen readers) read from the input value attribute or the text on screen?

If I have a form that updates via AJAX, there is a chance that the original value field (as it 开发者_C百科was output to the browser) will not match the text that the form field now has inside.

I know from a blind user that I help on occasion that Jaws 9 and later has strong support for rich internet applications (specifically AJAX and DOM changes) but I'm not sure if this support goes back as far as Jaws 7 (as their release history implies).

Basically, there are two concerns:

• If I load the form totally blank with no values set, and then use AJAX to load the data on page load (or after user hits a button), will Jaws read the inserted values?

• If I load the form with values set and those values change via AJAX will the reader read what is in the values or on screen?

My hope is that this is a case where deficiencies of the older versions will work to my favor, and that it always reads whatever is on screen (in the input fields) and disregards the values. And that it expects form values to change so it reads whatever is current, not just what loads.

But of course I'd rather know for sure rather than find out otherwise later.

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Screen readers interact with their own version of interfaces - a "virtual buffer". Screen readers (well, JAWS, at least) interacting with web pages actually seem to do a combination of reading nodes from the DOM and scanning what is displayed on the screen. So, I guess the answer is "it depends". As @pst suggests, there's no replacement for actually getting this tested, and by a screen reader user if at all possible.

Your options for solutions look a bit like this:

For a modern approach to communicating with assistive software like screen readers, check out WAI ARIA. Gez Lemon has written a good Introduction to WAI ARIA - well worth taking the time to read through.

Older screen readers are not good at updating the virtual buffer, but JAWS 7.1 and later provide developers with a mechanism for this. Again, Gez Lemon helps out here on his blog in Improving Ajax applications for JAWS users. If you want to delve deeper into this, there's some good background reading and research by James Edwards that's worth a read too.