A toggle is a switch that can be set to either an “on” or an “off” state. Toggle switches can be used to enable or disable features in software applications.
For example, a web site might use toggles to allow certain users to access articles that are otherwise only available to premium subscribers. A toggle is a simple and effective way to implement this feature, because it can be enabled or disabled at will, without the need to change code in multiple places.
Using toggles allows developers to make changes in small pieces and test them with real users. This approach makes it easier to identify issues and problems with new features before they are rolled out to the whole user base. In addition, by enabling and disabling features with toggles, developers can make sure that they aren’t breaking things that already work for most users.
Toggle switches should be clearly labeled so that they can be easily understood by the end-user. This means they should be designed to produce an immediate effect when clicked, and they should provide visual feedback when the toggle state changes. For example, a toggle should display a persistent “On” or “Off” status to reduce cognitive load on the user. It should also be positioned in an obvious location, and it should use clear colours to signal the current state of the system.
A toggle switch can be implemented by introducing a Boolean variable into the codebase and configuring it to change state depending on an event or action. The value of the variable can be determined by examining the state of the switch and taking an appropriate action depending on its state.
Savvy teams understand that Feature Toggles come with a carrying cost and seek to keep their inventory as low as possible. This requires a process for vetting whether toggles are the right method for a particular problem and a discipline to remove toggles that are no longer needed. Some teams even put “expiration dates” on their toggles to ensure that they are removed in a timely manner.
Many organizations use a centralized configuration approach to manage their toggles, such as an existing application DB or a dedicated toggles registry. This is often accompanied by a form of admin UI that allows system operators, testers and product managers to view and modify their configuration. This approach has the added benefit that toggle configuration lives side-by-side with code in source control, making it easy to track changes over time.
A variant of the toggle is an experiment flag, which is often used to perform multivariate or A/B testing in a production environment. An experiment flag will consistently send a given user down one or the other of two codepaths at runtime, and then analyze the results to determine which is more effective. This technique is commonly used to test changes such as ecommerce purchase flow or Call To Action wording, which would typically require a large scale and lengthy QA/testing process under more traditional waterfall development models.
