JS中间件设计模式的深入探讨与实例分析

function fn2(next){
  console.log('执行2，返回改造的next之前')
  return action => {
    console.log('执行2')
    next(action)
  }
}
function fn3(next){
  console.log('执行3，返回改造的next之前')
  return action => {
    console.log('执行3')
    next(action)
  }
}
function fn1(next){
  console.log('执行1，返回改造的next之前')
  return action => {
    console.log('执行1')
    getData().then( data => {
      next(action)
    })
  }
  
}
 
function getData(){
  return new Promise(resolve => {
    setTimeout( () => {
      resolve(true)
    },3000)
  })
}
const next = (action) => {
  console.log('action',action)
}
// compose([fn1,fn2,fn3])(next)
const mm = [fn1,fn2,fn3].reduce(function(a,b,currentIndex,arr){
  console.log("a",a)
  console.log("b",b)
  return function(...args){
    console.log('args',[...args][0].toString())
    return a(b(...args))
  }
})(next)(1)

function fn2(action){
  console.log('执行2，返回改造的next之前')
  action+2
}
function fn3(action){
  console.log('执行3，返回改造的next之前')
  action+1
}
function fn1(action){
  console.log('执行1，返回改造的next之前')
  return action+1
  
}
 
function getData(){
  return new Promise(resolve => {
    setTimeout( () => {
      resolve(true)
    },3000)
  })
}
const next = (action) => {
  console.log('action',action)
}
// compose([fn1,fn2,fn3])(next)
const mm = [fn1,fn2,fn3].reduce(function(a,b,currentIndex,arr){
  console.log("a",a)
  console.log("b",b)
  return function(...args){
    console.log('args',[...args])
    return a(b(...args))
  }
})(1)