HTML and CSS Reference
In-Depth Information
favorite sites (, Google's e-mail (, Amazon's A9
search engine (, and Microsoft Live (
Ajax Resources
Ajax is a very hot topic on the Web right now and there are many resources and articles
available. Some helpful sites are listed here:
1. Describe two uses of JavaScript.
2. Describe two uses of DHTML.
3. Describe two uses of Ajax.
11.13 Accessibility and
Focus on Accessibility
Multimedia and interactivity can help to create a compelling, engaging experience for
your Web site visitors. Please keep in mind that not every Web visitor will be able to
experience these features.
Provide links to free downloads for the plug-ins used by your multimedia. (The
code provided to incorporate Flash media and Quicktime media includes these
plug-in links.)
Text descriptions and equivalent content (such as captions) of audio and video
will provide access to those with hearing challenges.
When you work with multimedia developers and programmers to create Flash
animations or Java applets for your site, be sure to request features to provide
accessibility—keyboard access, text descriptions, and so on. If you use Flash, a
Java applet, or DHTML for site navigation—be sure it can be accessed with a
keyboard and/or provide plain text navigation links in the footer section of the
pages. Adobe provides a good resource for Web developers at their Accessibility
Resource Center (
Section 508 requires that certain rates of screen flickering (frequency greater than
2 Hz and lower than 55 Hz) are avoided. WCAG 2.0 guidelines (2.3.1) recommend
that a Web page not contain any item which flashes more than three times per sec-
ond. This is to prevent optically induced seizures. You may need to work with your
multimedia developer to ensure that dynamic effects perform within a safe range.
If you use JavaScript, be aware that some visitors may have JavaScript disabled
or are unable to manipulate the mouse. Section 508 requires that your site is
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