Dispatching states

In this chapter, we have learned that the dispatch function, provided by the useState hook, allows us to request a change of state any time we want to. The input argument that represents an action can be a string, a number, an object, an array, or any JavaScript expression:

  dispatch(state)
  dispatch({ state })
  dispatch([ state ])
  dispatch(null)

We know that, internally, the input argument supports a functional update format as well:

  dispatch(state => state + 1)

The benefit of using a functional update format here is that it has an opportunity to read the previous state before making a move toward the next state. This sometimes becomes useful if you build a new state that requires an old state.

A dispatched state is compared with the current state before making a final call if it changes. This means that not all dispatches end up with a state change. Take the following code as an example...