export let createStore = (reducer)=>{

    //定义默认的state

    let state;

    //定义默认的action

    let actionTypes = "@@redux/INIT"+Math.random();

    let initAction = {type:actionTypes}

    //将所以需要监听的函数放在这个里面

    let listeners = []

    //定义getState函数

    let getState = ()=>state;

    //定义事件订阅函数

    let subscribe = (cb)=>{

        listeners.push(cb);

    }

    //定义事件派发函数 用来调用action

    let dispatch = (action=initAction)=>{

        //调用reducer获取新的state

        state = reducer(state,action);

        //遍历所以需要监听的函数

        listeners.map((cb)=>{

            cb();

        })

    }

    dispatch();

    return {

        getState,

        dispatch,

        subscribe

    }

}