The word toggle is a verb meaning “to move or change between two states.” It’s commonly used in technology, computing, and programming to describe a button or switch that can be pressed or clicked to select one of two options. A toggle can be set to either “on” or “off,” and it can only be switched back to its original state by clicking or pressing again.
Feature toggles are great tools to use in a continuous delivery process because they allow your team to experiment with new functionality before rolling it out to your entire user base. Using a toggle to test how a new feature is received by your audience can help you identify potential bugs or confusion before the feature is rolled out in its entirety.
However, a toggle can also be misused. Adding a toggle to an existing product can lead to confusing and inconsistent behavior, so be sure that your team is careful when selecting the features that you want to put behind a toggle. For example, if you’re releasing an update that will enable the “hide sent messages” feature, make sure to test it with that toggle flipped off. This will prevent your users from accidentally sending messages while the toggle is on.
Most feature toggles are transitionary in nature and should only remain active for a short period of time. Once you have a solid idea of how a feature will be received, you can then retire the toggle. However, there are some situations in which a toggle may need to stay active for the lifetime of an application, such as serving as a circuit breaker during times of high latency.
In order to avoid confusing your users, toggles should be recognizable by movement and color to indicate their current state. If your toggle is pressed, it should change position and be highlighted with a brighter or more saturated color. Research has shown that utilizing these visual cues can reduce the number of mistakes and increase the confidence level of users when operating the toggle.
Another important consideration when designing a toggle is to ensure that it is accessible. Many web developers and designers use a more pronounced color to indicate the active toggle state, but this can be problematic for people with color blindness or low vision. If you’re not familiar with accessibility standards for your web platform, be sure to consult resources like the W3C’s Accessibility Guidelines for Web Programmers.
As your team continues to use feature toggles, it’s important that you plan for the removal of those toggles from the codebase. Some teams add a task on their backlogs to remove each toggle when they introduce it, and some even create “time bombs” that fail tests if a toggle has not been removed by an expiration date. While this strategy is certainly helpful for avoiding regressions, it’s important that your team considers each toggle on a case-by-case basis to ensure that you’re not creating more work for yourself in the long run.
