Evaluating Scripts

This page contains material related to a presentation at the Web Accessibility Best Practices Evaluation Training in Sankt Augustin, Germany on 25 October, 2005, as part of the WAI-TIES Project (WAI - Training, Implementation, Education, Support). It is not intended to stand-alone; rather, it is primarily provided as reference material for participants in the training.

Scope of Training and Materials: This one-day training focused on select topics that were particularly suited to the circumstances of this specific training session. It did not to cover all aspects of evaluating Web accessibility, and did not cover all Web Content Accessibility Guidelines (WCAG) 1.0 checkpoints.
No Endorsement or Recommendation of Evaluation Tools: W3C/WAI does not endorse Web accessibility evaluation tools and does not recommend one tool over another. Some tools were listed, demonstrated, and used in activities in this training. Mention of a specific tool does not imply endorsement nor recommendation. WAI does provide a comprehensive list of Evaluation, Repair, and Transformation Tools for Web Content Accessibility.

Evaluating Scripts

Script Fallback

6.3 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

Beware: some tools are satisfied with empty NOSCRIPT elements

Script Equivalent

...
<noscript>
  <p>YOUR BROWSER DOES NOT SUPPORT JAVASCRIPT!!!</p>
</noscript>
...

Example: Script Fallback 1

Before:

<script language="JavaScript" type="text/javascript">
  document.write('<table width="' + myWidth '">');
  ...

Example: Script Fallback 1

After:

<table id="fluid" width="100%">
<script language="JavaScript" type="text/javascript">
  document.fluid.width = myWidth;
  ...

Example: Script Fallback 2

Before:

<a href="javascript:function()">Link Text</a>

Example: Script Fallback 2

After:

<a href="redundant.html" onClick="function()"...

Example: Script Fallback 3

Before:

<select onchange="submit();">

Example: Script Fallback 3

After:

</select>
<input type="submit">

Script Fallback: Approach

Turn off scripts and use Web site
Analyze overall script function
Also consider security aspects

Obsolete Scripts

11.1 Use W3C technologies when they are available and appropriate for a task and use the latest versions when supported

Frequently applicable to decoration scripts such as rollover effect

Example: Rollover Script

Before:

<a href="page.html" onMouseOut="out(1)"
     onMouseOver="over(1)" ...>Link Text</a>

Example: Rollover Script

After:

<style type="text/css">
  a:hover { ... }
</style>
...
<a href="page.html" ...>Link Text</a>

Event Handlers

9.3 For scripts, specify logical event handlers rather than device-dependent event handlers
6.4 For scripts and applets, ensure that event handlers are input device-independent

Special case: applets and embedded objects with own user interface

Embedded Objects

8.1 Make programmatic elements such as scripts and applets directly accessible or compatible with assistive technologies [Priority 1 if functionality is important and not presented elsewhere, otherwise Priority 2]

Problem: difficult to evaluate third-party plugin software

Event Handlers: Approach

Disconnect mouse and use Web site
Search for even triggers such as:
- onClick, onMouseOver, ...

Other Checkpoints

7.1 Until user agents allow users to control flickering, avoid causing the screen to flicker
7.4 Until user agents provide the ability to stop the refresh, do not create periodically auto-refreshing pages
7.5 Until user agents provide the ability to stop auto-redirect, do not use markup to redirect pages automatically. Instead, configure the server to perform redirects
10.1 Until user agents allow users to turn off spawned windows, do not cause pop-ups or other windows to appear and do not change the current window without informing the user