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Re: JavaScript countdown timer for session timeout


From: Terence de Giere
Date: Jul 29, 2002 7:50AM


While a visual JavaScript countdown timer will be good for visual users
(assuming the text is large enough for everyone to read), it cannot
fulfill the 508 rules which require alternatives to browser side
scripting. One must consider what happens when scripting is not
available. If scripting is off, then the method for meeting the
requirements of paragraph (p) does not work. The JavaScript method is
least likely to work with the users that need it the most, and for whom
this rule was written. This is because JavaScript is an accessibility
problem in its own right.

Sometime back there was a lot of discussion of paragraph (p) on the
forum, you might look at the archives on the WebAim site and see what
was said. The main problem is interactive scripting often does not work
with assistive technology even when the scripting engine in the browser
is on. There are a lot of pros and cons to this requirement. For
security reasons a timeout is valuable, and extending the time can
reduce security.

Changes in the Web page, such as a pop up window can disorient users
with assistive technology, and in some cases does not work. If the user
is using a text browser like Lynx, nothing will happen. Some of the new
browsers (Mozilla, Opera) allow the user to surpress popup windows if
they want, as many people find them annoying. Accessibility guidelines
from the W3C for browsers include a requirement to allow the user to
turn off automatic secondary windows.

My feeling on this is the time extension should be a server side process
activated by form submission. This would save the users data already
entered, and return a page populated with that data with the time
extension. I don't think we solved the problem of how the user could
best be interactively informed time is running out if his/her system did
not support scripting. My solution was the user is informed by text on
the page that he/she has so many minutes to finish the form, and that
they must activate a "time extension button" that starts the process
described above. This method has the drawback that the user must keep
track of the time themselves, but a CGI script or servelet on the server
should work with all users whether they have a screen reader, an audio
browser, or a text browser, as long as the browser supports forms.

Does anyone have a better idea?

Terence de Giere

Joel Ward wrote:

JavaScript countdown timer for session timeout
"Joel Ward" < <EMAIL REMOVED> >
Thu, 25 Jul 2002 18:56:25 -0400

Hi everyone,

I have some questions about Section 508 item (p): When a timed
response is required, the user shall be alerted and given sufficient
time to indicate more time is required.

Scenario: We have some JavaScript that shows a countdown timer.
When, say, one minute is left in the client session (which is the
same as the server session/time out), a popup dialog will appear
that tells the user that the session will end soon. Then after the
time is up, the session times out if the user does not make any
selections (e.g. because they walked away).

I've read that this is an accepted method to handle Section 508 item
(p), and I think it's a good method for accessibility and usability
in general.

However, is the JavaScript countdown timer that is included with
this script an issue regarding 508 and/or accessibility? I tried the
script with JAWS 4.02, and the countdown timer did not interfere
with JAWS reading of the page, and the dialog boxes worked as well.

But does this dynamically changing text cause problems for some
users? Is it a good idea? It's only useful for visual users, of course.

Thanks! Joel P.S. Since this is regarding 508, we don't consider
what happens when JavaScript is turned off. In any case, other than
alerting the user of the server session time in the page text, we
can't really do anything if they have JavaScript turned off. But
officially for 508, it's okay that JavaScript is necessary. Yes, I
know this may leave out some users. But for this web application
JavaScript is required anyway, so anyone using it will need it to be
turned on.

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