[Mailman-Developers] Turning off dynamic JavaScript

[Laura Carlson]

--On Tuesday, July 4, 2006 9:44 PM +0200 emf wrote:

> I am determined to provide some JavaScript in the 'standard'
> interface, as it will make for enhanced ease-of-use for those sighted
> people using a modern browser.

Hi Ethan,

It says in 6.3 of WCAG 1.0 to "Ensure that pages are usable when 
scripts, applets, or other programmatic objects are turned off or not 
supported. If this is not possible, provide equivalent information on 
an alternative accessible page." [1]

Developers can use javascript as long as it degrades gracefully/is for 
progressive enhancement or if they provide an accessible alternative.

If developers want use JavaScript, then they also need to be very sure 
that what they write is accessible to devices like screen readers, 
magnification software, keyboard only control, voice-only control, 
feet-based mice. If developers are willing to support these situations 
in a responsible manner (thorough testing with real assistive 
technology users is key), then they can write JavaScript.

Current browser-based screenreaders do support javascript, but its 
practical scripting capabilities are nothing like the same as the 
browser used on its own (in terms of the interface elements it can use, 
and whether it can see/read updates to the DOM), yet you can't reliably 
detect the difference programmatically.

Heavyweight DOM scripting, often results in inaccessible content, 
because events used are mouse-specific and changes to the page are not 
always announced to users. The result might be perfectly accessible 
content on a page, but a screen reader user may not know that the new 
content exists or even if the user knows that it exists he probably 
doesn't know where to find it on the page.

Another difficulty often occurs when developers make things that look 
like controls on a page, but the information needed by assistive 
technologies like explicit labels are not present, and the 
accessibility and user experience for disabled users suffers.

It is fine to use javascript, unobtrusively, but, one should be aware 
of accessibility issues, and, if you don't NEED javascript for 
something that you can do it server side, often the server-side 
solution would make more sense.

It is far easier to deal with accessible JavaScript by ensuring that 
the core service being provided is not reliant on scripting. That way, 
if for some reason the JavaScript is inaccessible, it can be disabled 
in a browser, and thus the core functionality remains accessible. This 
is a safety net for developers, as well as visitors.

You can guarantee things server side. You can't client side. Maybe 100% 
of your users use javascript. Maybe 80% use it. Maybe some have figured 
out how to circumvent the javascript and submit invalid data to the 
server. Maybe they are not using the latest alternative devices that 
support Javascript. Maybe they are blind and hate the way many sites 
use javascript to manipulate the browser client-side making it hard for 
them to navigate from page to page and so have shut it off. Even people 
with perfectly modern computers who have 20/20 eyesight, full cognitive 
and motor skills will turn off Java Support in their browser.

The point is that all things being equal, it makes more sense to get 
the server-side logic working first, because it's more reliable. After 
that, use Javascript to enhance the usability features for the majority 
of users, without negatively affecting the accessibility. You should 
always fall back on a plain HTML or server-side solution for the 
benefit JavaScript provides.

In my opinion accessibility and Javascript boil down to one question: 
if you take away/disable javascript, will this prevent the user from 
accessing or retrieving the information?

Best regards,
Laura

[1] http://www.w3.org/TR/WAI-WEBCONTENT-TECHS/#tech-scripts

Related References:
http://www.d.umn.edu/goto/javascript#access
http://www.d.umn.edu/goto/javascript#ajaxaccess

___________________________________________
Laura L. Carlson
Information Technology Systems and Services
University of Minnesota Duluth
Duluth, MN U.S.A. 55812-3009
http://www.d.umn.edu/goto/webdesign/