Understanding Accidental Activation


This section contains the main explanatory content of the Understanding. It explains why the Guideline or Success Criterion exists and, at a high level, how to meet it.

People with various disabilities can inadvertently initiate touch or mouse events with unwanted results. Up-Event activation refers to the activation of a component when the trigger stimulus is released. For example, for touchscreen interaction the event would be triggered when a finger is lifted from the touchscreen at the end of a tap.There is a distinction between when someone touches a screen and when they remove their finger. On a mouse there is a difference between mouse down (initiating a click) and mouse up (releasing the finger). Authors can reduce the problem of users inadvertently triggering an action, by making activation on the up-event. This gives users the opportunity to move their finger or other pointer (e.g. mouse) away from the wrong target once they hit it. If touch down activation is necessary, there are several options:

Generic platform activation/click events generally trigger on up and when they do, they are also allowed. For example, in the case of mouse interactions, the "click" event in JavaScript triggers on release of the primary mouse button, and is an example of an implicit up-event.

Examples of where timing of the activation is essential would be:

Long press activation and 3D touch can be used as long as one of the above listed alternatives is present, and there is another conforming way to provide the action performed by the control.


This explains how following the success criterion benefits particular types of users with disabilities.


Examples in Understanding pages are normally simple lists of hand-waving examples. Sometimes, examples are instead provided in sub-sections with headings. In either case, examples should stay high-level and not get into code specifics, which is for techniques.




This section references techniques that can be used to meet the Guideline or Success Criterion. There are sub-sections for sufficient techniques, advisory techniques, and failures.

Remove any parts of the template that are not used, such as the section and heading for situations, sub-lists of techniques, or the "AND" construction. Also remove the square brackets around placeholder optional components.


Techniques that are sufficient to meet the Guideline or Success Criterion.



Techniques that are not sufficient by themselves to meet the Guideline or Success Criterion.

Same template as sufficient techniques.


Techniques that document conditions that would cause the page not to meet the Guideline or Success Criterion, even if sufficient techniques are also used.

Same template as sufficient techniques.