A toggle is a button-like element that has two states, on or off. It’s often used in places where a simple action can be either on or off, such as the caps lock key and the crouch button on a game console. A toggle can also be found in user interfaces as a way to enable or disable functionality like a checkbox, radio button or dropdown menu.
In software development, toggles are a UI component that enables developers to easily control what parts of an application are visible and hidden. In a GUI they are usually represented by an icon with the toggle symbol and can be activated via a click or keyboard shortcut.
While some systems can be configured with toggles via static files, this approach tends to become cumbersome at scale and is often accompanied by the need to deploy and re-deploy an artifact in order to modify its configuration. This adds a significant amount of friction to the CI/CD process and can impact the cycle time for validating a change and delivering it to production.
To address this issue, many organizations move their toggle configuration into some type of centralized store. Typically this is an existing application database and the move is accompanied by the build-out of some form of admin UI which allows system operators, testers and product managers to view and modify feature flags and their configuration. This solution is more performant, simpler to maintain and allows for runtime re-configuration of a toggle.
Savvy teams recognize that Feature Toggles come with a carrying cost and seek to keep their inventory as low as possible. To achieve this they have rules in place to ensure that a toggle is removed once it’s no longer required. This can be as simple as adding a task on the backlog for every toggle created or as complex as using an “expiration date” on a toggle which will cause a test to fail (or even refuse to start) if it is still in the codebase after the specified expiration date.
A toggle should only be used for actions that can be either on or off and where the change is immediately reversible. Use a different UI component, like a checkbox, in cases where you need more than two options or your change isn’t binary in nature.
Toggle can be a powerful UI tool for creating responsive, receptive applications that respond to users’ preferences and provide a consistent experience across devices and environments. But using it poorly can lead to confusing, unintuitive and difficult to manage UIs. By following these best practices you can avoid common pitfalls and create toggles that your users will love to use.
