A toggle is a switch that can be pushed to either its “on” or “off” position. It is commonly used in software when implementing options menus and similar interfaces. Toggles help users update preferences, settings and other types of information by enabling them to switch between two opposing states. They are typically used in situations where it would be more appropriate to use a checkbox or radio button as opposed to an entire form.
When designing a toggle it’s important to ensure that the user can easily understand its current state. This means using direct and clear labels that describe what the switch will do when it is pressed. It is also recommended that the toggle use visual cues to convey its current state such as the movement of a slider or color changes. It’s also a good idea to avoid relying solely on color as a visual signifier and instead include textual state descriptors which provide the same meaning to users from a different perspective. It’s also wise to consider societal and cultural implications when selecting a state for your toggle. For example using red for the on position may not make sense when working with audiences that associate this color with stop signs or traffic lights.
Toggles are also frequently used to perform multivariate or A/B testing. By assigning a specific toggle configuration to a cohort of users at runtime the toggle can consistently send that cohort down one code path or the other. The results of these tests can then be aggregated to compare the effectiveness of the alternative code paths.
While this approach is generally simple it can become cumbersome at scale and may require developers to manually re-deploy the artifact to test a change. For this reason many teams choose to move their feature toggles into a centralized configuration management system which allows them to be re-configured at runtime. This is often accompanied by the build-out of a simple UI which enables product managers, engineers and testers to view and modify the toggle configuration.
There are many ways to implement a toggle-based configuration management system. The most straightforward is to hardcode the configuration in the source code via a preprocessor’s #ifdef feature, although this approach can be difficult to maintain. Other more sophisticated approaches include storing the toggle configuration in an existing application DB or even in some cases allowing the toggle to be re-configured via API call.
When a toggle is being prepared for production it’s wise to always perform a complete set of regression tests which cover all the possible toggle configurations. This ensures that any new or legacy behavior which the team wishes to introduce is tested and will function as intended. It’s also a good idea that a fallback configuration is included where all the toggles which are planned to be released are flipped off in case any unexpected regressions emerge during testing or development.
