Change of Content

Summary

When people enter data or change the settings of controls, these actions should not cause unexpected changes in the content. People can become confused and unable to complete what they are doing when content changes in this way.

For example:

• Checking a checkbox should not automatically submit a form.
• Selecting an option in a list should not automatically launch a new browser window.

If entering data or changing a setting triggers an unexpected change of content, you must make people aware of this beforehand.

Overview

Forms often contain elements where people can change the settings of the elements. These elements are referred to as controls. Examples include a person selecting an option in a list, checking a radio button or checkbox, or entering text into a text field.

When a person changes the setting of one of these controls, the control should behave in a way that is expected. For example, a person can enter text in a textbox, and the focus will remain in the text input until the person navigates away from it. These predictable behaviours help people successfully navigate sites and complete tasks.

When changing the setting of a form control triggers an unexpected change, it can be extremely difficult for people to interact with a site. They may not be able to perceive or understand the changes. They may not know how to progress, how to get back to where they came from, or understand where they are on a page or within the site.

If changing the setting of a form control triggers an unexpected action, such as shifting focus, loading a new page, or launching a new browser window, users must be advised of this action before they interact with the control.