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Technique F59:Failure of Success Criterion 4.1.2 due to using script to make div or span a user interface control in HTML without providing a role for the control

About this Technique

This technique relates to 4.1.2: Name, Role, Value (Failure).

This failure applies to HTML.

Description

This failure demonstrates how using generic HTML elements to create user interface controls can make the controls inaccessible to assistive technology. Assistive technologies rely on knowledge of the role and current state of a component in order to provide that information to the user. Many HTML elements have well defined roles, such as links, buttons, text fields, etc. Generic elements such as div and span do not have any predefined roles. When these generic elements are used to create user interface controls in HTML the assistive technology may not have the necessary information to describe and interact with the control.

Note

Attaching event handlers to elements that are not normally interactive, such as span and div, can be disorienting to users. Even if care is taken to provide keyboard access to such elements, users may have a difficult time discovering that there are interactive controls in the content or understanding what type of behavior to expect from them. For example, users may not know which keystrokes are supported by the script to activate the element. Additionally, these elements do not generate the same operating system events as interactive elements, so assistive technology may not be notified when the user activates them.

Accessible Rich Internet Applications (WAI-ARIA) describes mechanisms to provide the necessary role and state information to create fully accessible user interface controls.

Examples

Example 1

The following example fails because it creates a checkbox using a span and an image.

<p> 
   <span onclick="toggleCheckbox('chkbox')"> 
     <img src="unchecked.gif" id="chkbox" alt=""> Include Signature 
   </span> 
</p>

Here is the scripting code which changes the image source when the span is clicked with the mouse.

var CHECKED = "check.gif"; 
var UNCHECKED = "unchecked.gif"; 
function toggleCheckbox(imgId) { 
  var theImg = document.getElementById(imgId); 
  if (theImg.src.lastIndexOf(CHECKED)!= -1) {
    theImg.src = UNCHECKED; 
    // additional code to implement unchecked action 
  } 
  else { 
    theImg.src = CHECKED; 
    // additional code to implement checked action 
  } 
}

A checkbox created in this manner will not work with assistive technology since there is no information that identifies it as a checkbox. In addition, this example is also not operable from the keyboard and would fail guideline 2.1.

Related Resources

No endorsement implied.

Tests

Procedure

  1. Examine the parsed source code for elements which have event handlers assigned within the mark-up or via scripting (indicating that the element is a user interface control).
  2. Check if the role of the control is already defined natively in the mark-up language.
  3. Check if another valid method, such as the assignment of a fitting WAI-ARIA role, has been used to define the role of the control.

Expected Results

If check #2 AND check #3 are false, the failure condition applies.

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