What is a Toggle?

A toggle is a piece of wood or plastic that is pushed through a loop or hole to fasten it. It is also used in computers and some other machines to switch between two functions, such as powering on or off. The toggle is usually labeled with an “On” and “Off” symbol, but it may be labeled in other ways as well. Toggle can also be a verb, such as “Toggle the lights.”

The term is often used in technology and computing to refer to any switch that changes a state or mode. In programming, toggles are usually a Boolean variable that can be set to one of two states, and when triggered, the variable changes state. Examples of this are the classic on/off buttons that control lights or other appliances, or toggles in websites and software programs that allow users to select different modes or options.

Feature Toggles are a way for a development team to test code in a production environment without risking all of the user data that might have been created had they committed the change to their master codebase. The dev team creates a toggle in their version control system that buckets their entire user base into two groups: those with the new toggle turned ON and those who have it turned OFF. This allows the team to see how the feature performs and catch bugs before it is rolled out to the whole population.

Toggle configuration can be stored in many places, including static files and a variety of application DBs. However, when a site becomes large enough that managing toggle configuration via files starts to become problematic, it is common for organizations to move the toggle config into some sort of centralized store, usually an existing application DB. This is often accompanied by the build-out of some form of admin UI which allows system operators, testers and product managers to view and modify features flags and their configuration.

It is important for teams to test toggles in their production environments, both when they are flipped ON and OFF. It is a good idea to have a process in place to prune toggles as soon as they have served their purpose, to prevent old toggles from lingering and affecting the user experience.

It is also important to note that toggles are not the best UI element for all situations, and that sometimes a button or other UI component is more appropriate. For example, some users have red/green color blindness, and using green as the toggle on/off indicator can be difficult for them to understand. It is important to consider this when designing a web page or application. There are a variety of other accessible alternative UI elements that can be used for the same functionality, such as checkboxes and radio buttons. These are generally more easily understood by people with color blindness, so they should be preferred when possible.