Toggle is a user interface element that helps users update settings, views, and content. When used well, toggles are clear to use, have a standard visual design, and deliver immediate results. Toggles should clearly identify the setting, view or content that it controls and update their appearance — typically by changing the background color — based on their current state. The surrounding context should also provide enough information to communicate the toggle’s role, such as “On” or “Off”.
In code a toggle is a Boolean variable that can be either True or False. Depending on the context, toggles can be used to implement a variety of user-facing features including the ability to switch between different themes in an application or to enable or disable features that are not required for a particular task.
When a feature needs to be updated and tested before being rolled out to all users (e.g., a change to an algorithm) it can be implemented as a toggle in the dev codebase. Once the toggle is flipped it can be tested in a subset of production users while leaving the original version of the code in the main branch of the codebase and continuing to push new releases to meet delivery targets.
Toggle configuration can be managed in a number of ways ranging from the simple approach of hardcoding a flag with a preprocessor’s #ifdef (which provides minimal dynamic re-configuration) to more complex approaches which rely on a centralized store (often an existing application DB) and a custom admin UI that system operators, testers and product managers can use to manage and modify Feature Flags and their toggle configuration. The centralized approaches are often better suited to a category of toggles like Permissioning Toggles that will usually live for long periods of time or be semi-permanent.
