A toggle is a switch that can be either on or off. Toggles can be found in many everyday technology devices as well as software applications. They are typically used to enable or disable features, switch between different display modes or otherwise configure settings.
In the world of Web Development, toggles can be used to implement responsive layouts or to control which parts of a site or application are visible to specific types of users. They can also be used to show/hide navigation menus, sidebars or other features based on user input.
When using toggles in a user interface it is important to think about accessibility. The WCAG 1.4.1 states that “Always avoid relying solely on color to convey meaning.” While some toggle switches might rely only on color, in most cases a toggle switch should be avoided for use with users who are blind or visually impaired. Using a toggle for these users might require more time to understand what the current state of the switch is, and may cause frustration or confusion if the incorrect action is taken.
Toggles can also be used to perform multivariate (A/B) testing. By exposing multiple codepaths to a cohort of users at runtime a toggle router can consistently send each user down one path or the other, and then collect data to measure the performance of both.
Using static files to manage toggle configuration can become cumbersome once your feature flag system reaches a certain scale, and managing updates manually can be challenging. To address this problem, many teams choose to move their toggle configuration into some type of centralized database where it is easy for developers, testers and product managers to view and modify.
