Web Site Accessibility
Guidelines for SCS Webmasters

What is Accessibility? - Making Your Web Site Accessible
Checklist for Accessibility
Must Have Items - Should Have Items - Try To Have Items
Items for More Experienced Webmasters
Apply These Items if Your Use These Special Features

Applets and Scripts

Rationale - Scripts

Scripts can interact with HTML source, which enables Web developers to enhance sites with dynamic content, visual effects, and client-side processing. Scripting on Web pages, specifically JavaScript, is now better supported by assistive technologies. Although some text-only browsers still don't support scripting, and individuals concerned with privacy and security may turn off scripting, this section will deal with the issues of accessing information affected by scripts.

Some of the functionality provided by scripts can help usability or, at least, not negatively affect accessibility. For example, JavaScript mouseovers used for visual effects, such as highlighting, are not an issue for accessibility for the blind and might improve usability for the learning impaired.

The accessibility goal is to make the functionality of scripts accessible from the keyboard, and the information (different from functionality) available to the assistive technology. If the script functionality and information is not accessible, the NOSCRIPT element is one technique used to provide an equivalent alternative.

Rationale - Applets

Most nongraphical browsers do not support applets. Many of these technologies were developed specifically for visual, audio, and interactive effects. When a Web site requires execution of these technologies, users of nongraphical browsers might not be able to access all of the important information unless you provide an equivalent alternative.

Techniques for Scripts and Applets

The following techniques may be used to meet the checkpoint described in the Special Features - Applets/Scripts section of the Checklist for Web Site Accessibility.

Alternatives for Scripts Using Event Handlers

Ensure that there are alternatives for links that can only be activated by an event handler. An event handler is a script that is invoked when a certain event occurs (e.g., the mouse moves, a key is pressed, the document is loaded, etc.). In HTML 4.01, event handlers are attached to elements via event handler attributes (the attributes beginning with "on", as in "onkeyup").

Some event handlers, when invoked, produce purely decorative effects such as highlighting an image or changing the color of an element's text. Other event handlers produce much more substantial effects, such as carrying out a calculation, providing important information to the user, or submitting a form.

For event handlers that do more than just change the presentation of an element, content developers should do the following to ensure accessibility:

• Use application-level event triggers rather than user interaction-level triggers. In HTML 4.01, application-level event attributes are "onfocus", "onblur" (the opposite of "onfocus"), and "onselect". These attributes are designed to be device-independent but are implemented as keyboard specific events in current browsers.
  
  
• If you must use device-dependent attributes, provide redundant input mechanisms. In other words, specify two handlers for the same element. Use "onmousedown" with "onkeydown". Use "onmouseup" with "onkeyup". Use "onclick" with "onkeypress". Do not write event handlers that use double-clicking ("ondblclick"). There is no keyboard equivalent in HTML 4.01.
  
  
• Do not write event handlers that rely on mouse coordinates because this will prevent device-independent input.
  
  
• Do not use the "onchange" event handler to trigger ACTION in a select menu. If you do, the menu will not work with the keyboard. Note that the "onchange" event can be used for other purposes, like changing the state of a check box. If "onchange" is used, focus must remain on the select menu.

Alternatives for Scripts

Scripts might create a barrier to accessibility when the capabilities are disabled in the browser or when the user is using a browser that cannot support scripts. If scripts are used to create content, and the user's browser does not support scripts, no content is generated or rendered. For example, when the information conveyed in a mouseover is necessary to understand or navigate the Web site, such as a pull-down menu, then alternative links must be available on the page to make the pull-down menu links accessible.

Some sites may require the page to be available without relying on scripts as the only means for delivering the functions. Techniques to ensure alternatives to scripts include:

• Providing an equivalent alternative with the NOSCRIPT element. The NOSCRIPT element contains HTML markup that will be displayed by browsers that do not support scripting or browsers with scripting turned off.
  
  Besides alternative content, the NOSCRIPT element can also contain a link to an alternative accessible Web page with the same content.
  
  For example:
  ...
  <body>
  <noscript><A HREF="snswtlist.htm"> SNS Worldwide</A></noscript>
  <script language="JavaScript">
  <!--
  function gotosite<formSpinbox> // This defines which form the script acts on
  { location.href = formSpinbox.pickWW.options[formSpinbox.pickWW.selectedIndex].value;
  // Points to the selected Index of the "pickWW" SELECT of the "formSpinbox" FORM.
  }
  // end the hiding comment -->
  </script>
  <FORM NAME="formSpinbox">
  <SELECT NAME="pickWW" onchange="return gotosite<this.form>;">
  <OPTION VALUE="snswtlist.htm#usa">America/USA</OPTION>
  <OPTION VALUE="snswtlist.htm#argentin">Argentina</OPTION>
  <OPTION VALUE="snswtlist.htm#australi">Australia</OPTION>
  </SELECT>
  </FORM>
  </body>
  ...
  
  
• Providing an equivalent alternative page that is accessible. The link to the text-only page could be a link with the page content.

Applets

Applets are programs designed to be executed or launched from within a Web page. Applets create a barrier to accessibility when the capability of running an applet is not supported by the browser or by the assistive technology being used. Even when the browser and assistive technology combination supports running applets, the content and programming might be inaccessible to the user.

If the applet programming and content cannot be made accessible, the accessibility goal is to inform the user of the existence of the applet and to provide an equivalent alternative in HTML. The following are techniques used to ensure accessibility and accessibility alternatives to applets:

• You must add alternative text to the APPLET element to make the user aware of the applet's purpose. For example:
  
  <applet code="gravity.class" width="200" height="250" alt="Java gravity applet">...</applet>
  
  
• Including equivalent HTML in the content of OBJECT elements. When the applet is not supported by the browser or by the assistive technology being used, the HTML content in the OBJECT element is rendered by the browser. For example:
  
  <OBJECT classid="java:gravity:class" width="200" height="250"> When gravity acts on an object, the weight...
  </OBJECT>

Testing

To ensure that your web page is accessible when using scripts:

• Test the page in a browser that does not support scripts or test the page in a browser with support for scripts disabled. If the NOSCRIPT element was used, the supported content is displayed. If equivalent alternatives were added to the page, they are displayed and are usable. If no equivalent alternatives are displayed and important content is not available, the web site is not accessible.
• Test the page with Internet Explorer using only the keyboard (no mouse) to test the accessibility of the site. If the site is accessible with a keyboard, the site will be fully functional.

To ensure that your web page is accessible when using applets, test the page in a browser that does not support applets or test the page in a browser with support for applets disabled. If alternative text was added to the APPLET element, the user is informed there is an applet on the site. If equivalent alternatives were added to the page, they are displayed and are usable. If no equivalent alternatives are displayed and important content is not available, the web site is not accessible.

What is Accessibility? - Making Your Web Site Accessible
Checklist for Accessibility
Must Have Items - Should Have Items - Try To Have Items
Items for More Experienced Webmasters
Apply These Items if Your Use These Special Features