A toggle is a switch that can be turned on or off to control an electronic device, often used for setting the alarm clock, changing the radio station, and starting or stopping the air conditioner. In computer science, toggle is also a mechanism for allowing a program to select between alternative execution paths. The toggle is typically implemented in a loop that runs continuously and compares the state of the machine to a predetermined set of states. If the state of the machine does not match one of the states in the list, the toggle is turned off and the loop is stopped.
Toggles are an important element in the development of responsive web design. They allow designers to change the way a site is displayed based on the user’s screen size and device. For example, a toggle could be used to hide navigation menus or sidebars when the screen is small. Similarly, a toggle could be used to display different layouts when the screen is larger.
The ability to use toggles in a responsive design approach means that a single application can be deployed on multiple platforms and devices. This allows organizations to reduce cost and complexity by only maintaining a single version of an application in production, while still delivering functionality to the appropriate audience.
Savvy teams view Feature Toggles as inventory that comes with a carrying cost and seek to minimize it by being proactive about removing toggles when they are no longer needed. To do this they employ a range of techniques, from adding toggle removal tasks to the team’s backlog to creating “time bombs” in their code that will fail a build or even refuse to start the application if a particular toggle is found.
While this approach can be effective, it can introduce a significant amount of friction into the testing process because every time a toggle is changed there must be a re-deployment of the test suite to reflect the change. This can be particularly disruptive for agile teams that strive to shorten the duration of their testing cycle in order to keep up with the rapid pace of product delivery.
Another issue with toggles is that they rely on visual cues such as color to signal their state. This can be problematic for users with accessibility needs, especially when those cues are not carefully selected. For instance, using red as the indication of an on state can be confusing for users with a red/green color blindness deficiency. Using high-contrast colors and incorporating state descriptors can help make toggles more accessible.