redux中间件applyMiddle实现原理

m1=function(next){
    return function(action){
        console.log("m1")
        next(action)
    }
}
m2=function(next){
    return function(action){
        console.log("m2")
        next(action)
    }
}

dispatch=function(action){
    console.log(action)
    return action
}

m1 m2代表中间件，手写调用dispatch方法即
m1(m2(dispatch))({action:1})
通过applyMiddle方法实现原理

applayMiddle=function(...args){
    args.unshift(dispatch)
    return args.reduce(function(dispatch,item){
        return item(dispatch)
    })
}

所以增强的dispatch相当于
增强的dispatch==applayMiddle(m1,m2)