A toggle is a user interface element that lets people manage the state of something—for example, whether it’s on or off. Toggles can help users update preferences, settings, and other kinds of information. Ideally, they should always have direct labels and use standard visual design. In addition, they should be clear about the effect they will have, delivering immediate results.
Toggles should be used when people need to change a single state of an object—not when they need to select from a list of options. For example, a switch might be more appropriate than a toggle for controlling a light, while a slider is better for controlling a color. In some cases, developers may want to use a toggle instead of a button to reduce the amount of screen space required on a mobile device.
In computer technology, a toggle is an on-and-off command, like the caps lock key. The word has a long history of meanings, from the 18th century “pin passed transversely through the eye of a rope to hold it fast” to its modern sense of changing between two states. It’s also a verb, meaning “to move or alternate between two things,” as in the way you might toggle between screens when video chatting with two friends at once.
Most web and app developers are familiar with toggle switches—small buttons that look like checkboxes but behave differently. They’re commonly used to enable and disable features. They can be confusing for some users, however. Toggle switches can be hard to understand because they don’t have an empty state and can have different appearances depending on their current state. This makes them difficult to read for people with dyslexia, motor disabilities or red/green color blindness.
Toggle configuration is often distributed across multiple files, and it can be challenging to update all of them at once. This can significantly slow down the validation process during a release cycle and impact the all-important feedback loop that CI/CD provides. Many teams choose to move feature toggle configuration into some sort of centralized store—usually an existing application DB—to facilitate updates and improve the overall testability of their products.
Toggle configuration is a critical tool for optimizing user experience. It can be challenging to keep track of and maintain across multiple environments, but it can provide powerful, data-driven insights into how changes affect real users. For these reasons, it’s important to plan carefully and test toggle configuration in production. It’s wise to perform a few tests with the toggle configuration that will be live in production, plus any toggles you intend to release flipped On. This will give you a good feel for any potential issues that could arise. It’s also a good idea to test the fallback configuration, where those toggles you intend to release are flipped Off. This will help you avoid any surprise regressions in a future release. This type of testing should be done in conjunction with the other types of test automation and manual exploratory tests that are necessary to cover your entire product set.
