Redux in <1kb

µredux.es6

const INIT = '@redux/INIT';

export const createStore = (reducer, state, enhancer) => {
  if (enhancer) {
    return enhancer(createStore)(reducer, state);
  }

  const subscribers = [];

  dispatch({ type: INIT });

  return {
    subscribe,
    dispatch,
    getState,
    replaceReducer,
  };

  function subscribe (listener) {
    subscribers.push(listener);
    const idx = subscribers.length - 1;
    return () => { delete subscribers[idx]; };
  }

  function dispatch (action) {
    state = reducer(state, action);
    subscribers.forEach(fn => fn());
  }

  function getState () {
    return state;
  }

  function replaceReducer (next) {
    reducer = next;
    dispatch({ type: INIT });
  }
};