# Understanding On Input

## In brief

Goal
  Content can be operated more predictably.
What to do
  Forewarn users if their context will change based on their input.
Why it's important
  Content that behaves predictably is especially important to people with disabilities.

## Intent of On Input

The intent of this Success Criterion is to ensure that entering data or selecting a form control has predictable effects. Changing the setting of any user interface component is changing some aspect in the control that will persist when the user is no longer interacting with it. So checking a checkbox, entering text into a text field, or changing the selected option in a list control changes its setting, but activating a link or a button does not. Changes in context can confuse users who do not easily perceive the change or are easily distracted by changes. Changes of context are appropriate only when it is clear that such a change will happen in response to the user's action.

This Success Criterion covers changes in context due to changing the setting of a control. Clicking on links or buttons is activating a control, not changing the setting of that control.

What is meant by "component" and "user interface component" here is also sometimes called "user interface element".

## Benefits of On Input

- This Success Criterion helps users with disabilities by making interactive content more predictable. Unexpected changes of context can be so disorienting for users with visual disabilities or cognitive limitations that they are unable to use the content.

- Individuals who are unable to detect changes of context are less likely to become disoriented while navigating a site. For example:

  - Individuals who are blind or have low vision may have difficulty knowing when a visual context change has occurred, such as a new window popping up. In this case, warning users of context changes in advance minimizes confusion when the user discovers that the back button no longer behaves as expected.
- Some individuals with low vision, with reading and intellectual disabilities, and others who have difficulty interpreting visual cues may benefit from additional cues in order to detect changes of context.

## Examples of On Input

- A form is provided for creating calendar entries in a Web based calendaring and scheduling application. Along with the standard fields for subject, time and location, there is a set of radio buttons to select the type of calendar entry to create. The calendar entry type can be meeting, appointment or reminder. If the user selects the radio for meeting, additional fields are displayed on the page for entering the meeting participants. Different fields appear if the reminder button is chosen. Because only parts of the entry change and the overall structure remains the same the basic context remains for the user.
- A form contains fields representing US phone numbers. All of the numbers have a three digit area code followed by a three digit prefix and finally a four digit number, and each part of the phone number is entered into a separate field. When the user completes the entry of one field the focus automatically moves to the next field of the phone number. This behavior of phone fields is described for the user at the beginning of the form.

## Resources for On Input

## Techniques for On Input

### Sufficient Techniques for On Input

- Providing a submit button to initiate a change of context using a technology-specific technique listed below

  - Providing submit buttons
  - Using a button with a select element to perform an action
- Describing what will happen before a change to a form control is made

A change of content is not always a change of context. This success criterion is automatically met if changes in content are not also changes of context.

### Additional Techniques (Advisory) for On Input

- Giving users advanced warning when opening a new window

### Failures for On Input

- Failure due to automatically submitting a form and presenting new content without prior warning when the last field in the form is given a value
- Failure due to launching a new window without prior warning when the status of a radio button, check box or select list is changed