What Is a Toggle?

A toggle is a button or switch that enforces an on/off state. It’s a type of feature flag that enables teams to easily and rapidly turn features on or off based upon user context, experiment results, or product direction.

In software development toggles are commonly used to enable multivariate or A/B testing. They can be used to control things like the default color of a button, whether or not it shows an error message on page load, the text of a Call To Action (CTA) phrase, or even which website language is served to a visitor based on their browser preference. The ability to quickly and easily make data-driven optimizations across the entire userbase is a core capability of many modern web applications.

There are some important design issues to consider when implementing toggles. For example, toggles can be confusing if they aren’t designed with the principle of proximity in mind. For example, if a toggle has two labels it’s important that they are positioned next to each other so that users can see them at the same time and understand what the toggle is in its current state. This is important to prevent cognitive overload.

Also, if a toggle only has one label it’s important that the label is clear enough to describe what will happen when the toggle is pressed in its current state. This is especially important if the toggle is likely to be confused with other types of switches such as checkboxes or radio buttons. Finally, it’s best to avoid toggles in situations where users need to tap a Save or Confirm button for the toggle to take effect. For example, it’s usually better to use a simple checkbox than a toggle in long forms where users will need to wait for the form submission to complete before they can see the impact of their change.

Toggle Configuration

Managing toggle configuration with static files can get cumbersome once you reach a certain size and it’s hard to make changes consistently across a large fleet of servers. As such, many companies choose to move their toggle configuration into some form of centralized store, often an existing application DB. In addition to providing a more dynamic approach for managing toggles this also makes it easier for testers and product managers to modify toggles and their settings from the same place.

Finally, it’s important to make sure that a team thoroughly tests the toggle configuration that they expect to deploy into production. This will typically mean testing the toggle with its current state flipped Off and then testing it with its current state flipped On. In some cases a team may want to test with both toggles flipped On as well, but this should be done with extreme care to ensure that there are no hidden regressions in the behavior of a system when it is running with its expected and desired toggle configuration.