Easy Peasy v5

# reducer

Declares a section of state to be calculated via a "standard" reducer function - as is typical in Redux.

This API specifically exists to help with integrations against existing Redux based libraries, and to help with gradual migration from legacy Redux code.

For example redux-first-history (opens new window), requires you to attach a reducer that they provide to your store.

reducer((state = 1, action) => {
  switch (action.type) {
    case 'INCREMENT':
      state + 1;
    default:
      return state;
  }
});

# API

The reducer function is described below.

# Arguments

  • reducer (Function, required)

    The reducer function. It receives the following arguments.

    • state (Object, required)

      The current value of the property that the reducer was attached to.

    • action (Object, required)

      The action object, typically with the following shape.

      • type (string, required)

        The name of the action.

      • payload (any)

        Any payload that was provided to the action.

  • config (Object)

    An optional object to configure the reducer.

    • immer (Boolean) Whether to use immer to update the state. Defaults to true.

      You may want to consider disabling immer when dealing with a large/deep data structure within your state. Immer does unfortunately have an overhead as it wraps data in a Proxy solution for the mutation based updates to work. We would suggest only using this escape hatch if you are noticing any performance degradation.

# Example

import {
  createStore,
  reducer,
  useStoreState,
  useStoreDispatch,
} from 'easy-peasy';

const store = createStore({
  counter: reducer((state = 1, action) => {
    switch (action.type) {
      case 'INCREMENT':
        return state + 1;
      default:
        return state;
    }
  }),
});

function Counter() {
  const count = useStoreState((state) => state.counter);
  const dispatch = useStoreDispatch();
  return (
    <button onClick={() => dispatch({ type: 'INCREMENT' })}>{count}</button>
  );
}

← thunkOn →