Skip redux subscription updates when state hasn't changed

skip-same-state-enhancer.js

import { createStore as basicCreateStore } from 'redux';

export const skipSameStateEnhancer = createStore => (
  reducer,
  initialState,
  enhancer,
) => {
  const store = createStore(reducer, initialState, enhancer);

  // Create an in-between store so that we can skip subscription updates where nothing changed.
  // Using basicCreateStore to not mess with e.g. redux-dev-tools. Not sure if it matters.
  const subStore = basicCreateStore(() => {});
  let cachedState = store.getState();

  store.subscribe(() => {
    const state = store.getState();
    if (state !== cachedState) {
      cachedState = state;
      subStore.dispatch({ type: 'trigger' });
    }
  });

  return {
    ...store,
    subscribe: subStore.subscribe,
  };
};