A toggle is a switch or button that can be pushed to change from one state or mode to another. They are used in many everyday technologies such as computers, smartphones and video chats. You can also find them in some other products like air traffic control systems and military equipment. In web design, toggles can be found as a way to allow visitors to select different content layouts such as sidebar menus and collapsible sections.
While toggles can be helpful, it’s important to keep in mind that they come with a carrying cost of managing them. It is important to minimize the number of toggles in your codebase and to remove them as soon as they are no longer needed. Savvy teams look at their inventory of toggles as an asset that comes with a price tag and they seek to keep it as low as possible. This can be done by adding a toggle removal task to the team backlog or building a process into their management platform.
It is often tempting to put large swaths of your code under the control of a complex set of toggles. This is typically a bad idea and will lead to a complex set of dependencies that can be difficult to manage. It is also likely to create a significant amount of code duplication, resulting in slower codebase growth and potentially bugs that could be hard to find.
When using Feature Toggles it’s important to test them consistently and thoroughly. It’s best to test the toggle configuration that you expect to be live in production, along with any toggles that you intend to release flipped On and any toggles that you will be releasing flipped Off. This helps avoid surprise regressions when a toggle is flipped in production and helps ensure that the system tests cover all possible toggle configurations.
One common mistake is to use a toggle to implement something that would be better implemented with a checkbox. For example, a toggle may be used to enable download functionality in an app but it’s important to remember that downloading is a one-time event and doesn’t require a persistent state. It would be much more appropriate to use a checkbox or a button with the aria-pressed attribute.
Finally, it’s important to remember that a feature flag is just a piece of configuration. It is important to build in some method for centralized storage of toggle configurations, often in the form of a centralized database or application config file. This can make it easy for developers to access and modify toggle configuration and can reduce the need to re-deploy the whole artifact into testing environments to flip a single toggle. This can have a significant impact on the speed of your CI/CD process and should be avoided when possible. It’s also a good idea to build out an admin UI that allows system operators, testers and product managers to view and modify toggle configuration.
