3.2.2: On Input

What it means

Changing a control’s setting must not automatically change context unless the user was warned beforehand. Submit buttons should confirm navigation — not every dropdown change.

Unexpected redirects after selecting an option cause lost data.

How to fix it

• Use a Submit button after users change settings that would reload the page.
• Warn if changing a select will navigate away (for example language switcher).
• Keep filter changes updating the same page without surprise redirects.
• Preserve form data when users adjust non-submit controls.

Quick examples

• Good: Changing sort order refreshes the product list in place with no redirect.
• Bad: Selecting a billing country instantly submits the form and charges the card.
• Good: Language switcher warns “You will leave this page” before navigating.
• Bad: Checking a newsletter box redirects to a signup page without warning.