react-sweet-state/lib/esm/store/create-state.js

Global + local state combining the best of Redux and Context API

import applyMiddleware from '../middlewares';
import withDevtools from '../enhancers/devtools';
import defaults from '../defaults';
import schedule from '../utils/schedule';

function createStoreState(key, initialState) {
  let listeners = new Set();
  let currentState = initialState;
  const storeState = {
    key,

    getState() {
      return currentState;
    },

    setState(nextState) {
      currentState = nextState; // Instead of notifying all handlers immediately, we wait next tick
      // so multiple actions affecting the same store gets combined

      schedule(storeState.notify);
    },

    resetState() {
      storeState.setState(initialState);
    },

    notify() {
      for (const listener of listeners) {
        listener(storeState.getState());
      }
    },

    subscribe(listener) {
      listeners.add(listener);
      return function unsubscribe() {
        listeners.delete(listener);
      };
    },

    listeners() {
      return listeners;
    }

  };
  storeState.mutator = applyMiddleware(storeState, defaults.middlewares);
  return storeState;
}

export default withDevtools(createStoreState);