Overview

Scripting languages allow developers to create more interactive Web pages, to process information, and to control page content. There are two types of scripting languages: server-side and client-side.

Server-side scripting performs all of its processing on the web server and then delivers its final product (a Web page or content) to the user's browser. Server-side scripting does not, in and of itself, present accessibility problems. Like all web content, however, server-side scripts must produce content that follows the principles of accessible design.

In contrast, client-side scripting is scripting that does all of its processing on the user's own computer. It is commonly used to create pop-up windows, instant-redirects, pulldown menus, shopping-cart calculations, and mouseover effects.

Whether client-side scripts yield accessible content depends largely on how they are used and whether the user has the technology to support them. Scripts can cause accessibility problems by preventing keyboard access to Web features, by presenting content or functionality that is not accessible to assistive technology devices, by limiting user control over automated content changes, and by modifying the normal functionality of the browser.

All content and functionality presented by a script should be available to assistive technology devices such as screen readers or screen magnifiers. The only way to ensure accessibility is to evaluate each individual script and devise a unique solution if accessibility problems are discovered. Content written to the page using JavaScript or a similar scripting technology is generally accessible if:

• Device-independent event handlers and controls are used
  
  
• Script content and functionality is accessible to assistive technologies
  
  
• Scripted pages and elements can be navigated using a keyboard
  
  
• The normal browser functionality is not modified in a way that may cause confusion or inaccessibility
  
  
• An accessible alternative is provided when the script cannot be made natively accessible
  
  

Scripts that are used to make cosmetic changes (for example, a mouseover to change the color of a button when it is pressed) are generally accessible as long as the content does not change or as long as techniques have been used to ensure its accessibility.

Most of the information about accessible scripting presented on these pages pertains to JavaScript. However, these guidelines apply to all Web scripting methods. Web developers are expected to be familiar with the accessibility issues presented by JavaScript, to translate this information as it relates to their own development environments, and to provide equivalents as they are discovered so that this section can be updated.