A toggle is a switch that allows you to switch between two states or options. It’s used in technology, computing, and programming to give users a simple way to update preferences or settings. Toggles are often based on the idea of a pin passed through a loop or eye to fasten something, but they’re also found in everyday technology like keyboards (Caps Lock and Num Lock), phones, and video chat services (which toggle between screens as you talk to two people at once). Toggle switches can be either on or off.
As a user-interface element, toggles are fairly common because they’re easy to understand. They’re especially useful in situations that require a clear choice between two opposing options, such as the ability to choose between multiple languages for a phone app or an account setting.
Toggle switches should be paired with direct labels and standardized visual design. For example, a toggle with an on/off icon should always be labeled as such; it should never have a name like “Turn off”. Also, it’s important to use standard form elements for toggles – radio buttons and checkboxes convey the same information more clearly than text-based alternatives.
One of the downsides to using toggles is that they can be hard to test and debug. Unless they’re configured as dynamically re-configurable in a runtime environment, it can be difficult to tell whether the toggle is actually changing the behavior of your application. Depending on the design of your toggle configuration system this can be mitigated by moving them to some type of centralized store, but even that can become cumbersome when you reach certain scales.
Another important consideration is that toggles can be hard to understand for users with disabilities. Unless they’re paired with a standardized visual design, toggles can be cognitively confusing for users who rely on assistive technologies such as screen readers. This can be overcome by making sure that toggles are properly configured for accessibility and by avoiding using color as the only means of conveying the current state (WCAG guideline 1.4.1).
A key aspect to implementing a good toggle configuration system is its ability to allow you to dynamically re-configure a specific service instance. If you’re forced to rely on static files or manual methods of configuring individual instances of your application then it may be impossible to run automated tests and it can significantly slow down the cycle time for validation. A feature flag system that supports this is usually the best approach. This can be accomplished by exposing an endpoint that will automatically re-configure the toggle for a specific service instance, rather than forcing you to manually re-deploy and re-test an artifact every time the toggle changes. This will not only speed up your CI/CD process, but it’ll also make your testing and debugging much easier for you and your team.
