Toggle is a control that quickly switches between two possible states. They are used for binary actions that occur immediately after the user “flips the switch”. Toggle switches should be simple to understand and deliver immediate results. They should have direct labels, be positioned in a clear manner, and utilize visual cues to convey state change.
Savvy teams view the Feature Toggles in their codebase as inventory which comes with a carrying cost, and seek to keep this inventory low by being proactive about removing toggles that are no longer needed. To this end some teams have rules for adding a toggle removal task to the team backlog on every new Release Toggle, while others use “expiration dates” that cause a test to fail if a toggle has not been flipped to the desired state in time.
The word toggle is an old nautical term referring to a pin passed through the eye of a rope or other fastener and capable of switching between two positions. It’s still often used for a kind of on/off switch, such as the Caps Lock or Num Lock keys on a keyboard.
As a software engineering concept the toggle is a useful tool for managing a Feature Flag’s configuration at runtime. Many organizations choose to manage this configuration via static files, but this approach can get cumbersome at scale and requires developers and testers to be vigilant about ensuring that the toggle is always pointing to the correct value. In order to avoid this and improve the overall speed and quality of the CI/CD process many organizations opt to move Toggle Configuration into some sort of centralized store, often an existing application DB.