JavaScript事件发布/订阅模式原理与用法分析

class AsyncFunArr {
 constructor (...arr) {
  this.funcArr = [...arr]
 }
 next () {
  const fn = this.funcArr.shift()
  if (typeof fn === 'function') fn()
 }
 run () {
  this.next()
 }
}

//将fn1,fn2,fn3订阅
const asyncFunArr = new AsyncFunArr(fn1, fn2, fn3)
//fn1，fn2，fn3作为分布者分别调用其next()方法
function fn1 () {
 console.log('Function 1')
 asyncFunArr.next()
}
function fn2 () {
 setTimeout(() => {
  console.log('Function 2')
  asyncFunArr.next()
 }, 500)
}
function fn3 () {
 console.log('Function 3')
 asyncFunArr.next()
}