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HTML and scripting
User Agent and Assistive Technology Support Notes
This failure relates to:
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.
See the resources section below for links to specifications which describe mechanisms to provide the necessary role and state information to create fully accessible user interface controls.
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.
Resources are for information purposes only, no endorsement implied.
Examine the source code for elements which have event handlers assigned within the markup or via scripting.
If those elements are acting as user interface controls, check that the role of the control is defined.
If check #2 is false and the created user interface control does not have role information, this failure condition applies.