simpleCreateStore

[ZWkang]

const createStore = (reducer) > {
  let state;
  let listeners = [];
  const getState = () => state;
  const dispatch = (action) => {
    state = reduce(state, action);
    listeners.forEach(listener => listener());
  }
  const subscribe = (listener) => {
    listeners.push(listener);
    return () => {
      listeners = listeners.filter(l => l !== listener)
    };
  }
  dispatch( {} )
  return { getState, dispatch, subscribe};
}

// 接受多个reducer
// 对state做遍历执行 找到对应的reducer然后进行处理。
const combineReducers = (reducers) => {
    return (state = {} ,action )=>{
        return Object.keys(reducers).reduce(
            (nextState,key) => {
                 nextState[key] = reducers[key](state[key],action);
                 return nextState
            },
            {}
        )
    }
}