函数组合 compose redux-saga koa 洋葱模型

Question

问题

const middleWare = []
middleWare.push(function (next) {
   console.log(1)
   next()
   console.log(2)
})
middleWare.push(function(next) {
   console.log(3)
   next()
   console.log(4)
})
middleWare.push(function(next) {
   console.log(5)
   next()
   console.log(6)
})
const fn = compose(middleWare)
fn() // 1,3,5,6,4,2

答案

function compose(middleWare) {
  const fns = middleWare.slice(0)
  const next = function () {
    while(fns.length) {
      const fn = fns.shift()
      fn(next)
    }
  }
  return () => next()
}