The word toggle has several meanings, including a pin passed transversely through the eye of a rope or chain to bind it temporarily (the same way your caps lock key toggles between the two settings). However, in software development it most commonly refers to an on/off command. Toggles are a useful way to enable and disable features. However, if they aren’t used correctly they can do more harm than good. The first thing to remember when using toggles is that they should only be used as controls for actions that will have an immediate effect without requiring any additional user input. Otherwise, other controls like radio buttons or checkboxes should be used instead.
The next thing to keep in mind when using toggles is that users must be able to discern whether a switch is active or not. This requires the use of a visual cue. One common approach is to use a more pronounced, saturated color for the active option and a lighter color for the inactive option. However, this method has been found to be unreliable and prone to confusion. In fact, a recent study found that it was more effective to use a combination of visual cues than simply a single color.
Another way to help users understand the current state of a toggle is to display it with an icon. This is often easier to read than text alone, especially when the toggle’s text is small or obscured by other elements. The best icons tend to be simple, recognizable, and easy to read. Avoid ones that are too elaborate or that require the user to interpret an image in order to understand what the toggle is currently doing.
Savvy teams recognize that Feature Toggles come with a carrying cost, and they seek to minimize the number of toggles in their codebase. This typically involves making it clear to testers which toggles are active, and putting “expiration dates” on those that will be deprecated in a future release. Some teams even go as far as creating a “time bomb” in their test suites that will fail the test (or even refuse to start the application) if a toggle has not been updated for more than a week.
Finally, it’s worth mentioning that many savvy teams move Toggle Configuration away from static files and into some type of centralized store, typically an existing application DB. This makes it much easier to make changes and ensure consistency. However, it’s important to always test the production toggle configuration as well as a fallback configuration where all of the intended future toggles are flipped off. This helps to protect against unexpected regressions in a new release.
