factoryhr

var actionTypes = {
  increment: 'increment',
  decrement: 'decrement',
};

factoryhr

function incrementAction(value) {
  return {
    type: actionTypes.increment,
  };
}

function decrementAction(value) {
  return {
    type: actionTypes.increment,
  };

factoryhr

var initialState = {
  counter: 0,
};

factoryhr

function incrementHandler(state, action) {
  var nextState = Object.assign({}, state);
  nextState.counter += 1;
  return nextState;
}

function decrementHandler(state, action) {
  var nextState = Object.assign({}, state);
  nextState.counter -= 1;
  return nextState;

factoryhr

function counterReducer(state, action) {
  switch (action.type) {
    case actionTypes.increment:
      return incrementHandler(state, action);
    case actionTypes.decrement:
      return decrementHandler(state, action);
    default:
      return state;
  }
}

factoryhr

function createStore(reducer, preloadedState) {
  // Our store implementation will go here...
}

factoryhr

function createStore(reducer, preloadedState) {
  // Store the current state
  var currentState = preloadedState;
  
  // Retrieve the current state
  function getState() {
    return currentState;
  }
  
  // Expose the API

factoryhr

function createStore(reducer, preloadedState) {
  var currentState = preloadedState;
  // Keep track of all listeners
  var listeners = [];

  function getState() {
    return currentState;
  }

  // Subscribe new listeners to the store

factoryhr

function createStore(reducer, preloadedState) {
  var currentState = preloadedState;
  var listeners = [];

  function getState() {
    return currentState;
  }

  function subscribe(listener) {
    listeners.push(listener);

factoryhr

function createStore(reducer, preloadedState) {
  if (typeof reducer !== 'function') {
    throw new Error('Expected `reducer` to be a function.');
  }

  if (typeof preloadedState === 'function') {
    console.warn(
      'Received function as `preloadedState`. ' +
      'State is undefined.'
    );