Learning Redux

Higher-order reducers

As we discussed in the previous chapters, Redux reducers are simply functions. This means that we can apply the same pattern to them and create higher-order reducer functions (or, in short, higher-order reducers).

A higher-order function is a function that returns a function (and/or takes a function as an argument). A higher-order reducer is a reducer that returns a reducer (and/or takes a reducer as an argument).

For example, a higher-order reducer that simply calls the reducer (effectively not doing anything special) will look like this:

function doNothingWith (reducer) {  return function (state, action) {    return reducer(state, action)  }}

In fact, the preceding example is both types of higher-order function: It takes ...