Toggle is a term used in software development to describe a switch with two positions – on and off. Toggle switches are used to change the state of a variable in an application, for example to determine which actions or events trigger when a button is clicked. The variable can then be used to control other parts of the program. Toggles are typically used to implement event driven programming and have a visible focus state, ensuring they are accessible for users with disabilities.
Similarly, toggles are also used in user interfaces as a means to allow users to control aspects of an app such as theme or layout. For example, a toggle can be used to switch between light and dark themes in a responsive web design. Toggles can be implemented using various methods in JS, for example by creating a listener and adding it to the element with an ID attribute or a DOM method such as jQuery.
The word toggle comes from the verb to toggle, meaning to move back and forth between two states. This can be done physically, for example by hitting a button to toggle crouch during an Aim bot game, or in software by clicking a button to toggle between multiple views on a video chat window. Toggle is also commonly used to refer to a UI feature, such as the ability to switch between stream and map view in a live stream.
In addition to their use in UIs toggles are often employed in software engineering as a tool for managing complexity and allowing teams to experiment with different options without impacting production code. This can be particularly useful when implementing a new feature or fixing bugs, as it ensures that a fix doesn’t accidentally make the bug worse and can also be helpful to identify which codepaths should remain open for future product improvement efforts.
While this approach is generally preferable it does come with some drawbacks, the most notable being that toggle configuration cannot be changed dynamically. This may be acceptable for some types of toggles, especially release toggles, but it’s less suited for Ops Toggles or Permissioning Toggles.
One solution for this is to hardcode toggle configuration into the code, using either a commented approach or a preprocessor’s #ifdef features where possible. This is generally acceptable for short-lived toggles and allows the toggle to be re-configured without rolling out a full release, but it is not suitable for Ops Toggles or Permissioning toggles where the re-configuration should be made on a continuous basis. For these more long-lived toggles, a more sophisticated approach such as an external feature flag service is often needed.
