Toggle is a type of user interface control that allows users to set and change some aspect of their experience. Generally toggles are used to update settings, views and content. However they can also be used to turn features on and off. When implementing toggles it is important to think about how they are going to be used by users and to make sure that the toggle’s current state is clear to them. Using direct labels and consistent visual design can help to reduce cognitive overload when using toggles.
While toggles have a number of benefits, it is important to remember that they do add complexity to the codebase. For this reason it is a good idea to only use toggles when necessary. When a team does decide to use toggles, they should be careful to use them sparingly and ensure that the code that implements them is well tested. Typically teams will test the toggle configuration that they expect to be live in production as well as any toggles that they are planning to release with a “fallback” configuration (with those toggles flipped off).
The word toggle is derived from a verb, toggling, which means to move or shift back and forth. It can also mean to move or shift a pin, bolt or rod transversely through an eye or loop in a chain, rope etc, so as to bind it temporarily. A toggle is also a device or system for fastening a toggle rail to a frame of a house or building.
As a general rule of thumb, Feature Toggle’s should only be enabled when they will improve or simplify a users experience. For example, a Toggle that allows an ecommerce system to offer free shipping for orders above $100 should only be activated when it will boost conversion rates. Similarly, a Toggle that enables users to choose between multiple video resolutions for streaming videos should only be enabled when it will improve user experience or deliver more value to the end customer.
Another common use for Feature Toggles is to run multivariate or A/B testing. In this case a Toggle will be configured to consistently send each individual user down one of two different codepaths depending on their cohort. This can be a powerful tool to use for making data-driven improvements in things like the purchase flow of an ecommerce site or the Call To Action wording on a button.
Managing Toggle configuration via static files becomes cumbersome at a certain scale and so many organizations move their Toggle Configuration into some sort of centralized store, often an existing application DB. This is usually accompanied by the build-out of some sort of admin UI which lets system operators, testers and product managers view and modify the Toggle’s configuration.
Lastly, it’s important that teams are proactive about removing toggles once they have run their course. Leaving idle toggles in the codebase can have a negative impact on performance and on the maintenance costs of an application. Savvy teams will typically include a task in their team backlog or build-in a process into their feature management software that prompts them to remove old Toggles from the codebase.