A reducer is a function that determines changes to an application’s state. It uses the action it receives to determine this change. We have tools, like Redux, that help manage an application’s state changes in a single store so that they behave consistently.
Why do we mention Redux when talking about reducers? Redux relies heavily on reducer functions that take the previous state and an action in order to execute the next state.
We’re going to focus squarely on … Read article “Understanding How Reducers are Used in Redux”