关于redux:函数合成compose的多种实现原理

// 责任链模型（一个接一个执行）

const fn1 = (x, y) => x + y;const fn2 = (z) => z * z;

// 失常组合

const compose = (fn1, ...other) => (...args) => {  let ret = fn1(...args);  other.forEach(item => {    ret = item(ret);  });  return ret;}

// redux 中间件组合形式

const reduxCompose = (...fns) => fns.reduce((a, b) => (...args) => b(a(...args)))const fn = reduxCompose(fn1, fn2);console.log(fn(1, 2));

// 洋葱圈模型（一半一半执行）

const koaCompose = (middlewares) => {  return function () {    return dispatch(0);    function dispatch(idx) {      const fn = middlewares[idx];      if (!fn) {        return Promise.resolve();      }      return Promise.resolve(        fn(function next() {          return dispatch(idx + 1)        })      )    }  }};async function func1(next) {  console.log("func1");  await next();  console.log("func1 end");}async function func2(next) {  console.log("func2");  await delay();  await next();  console.log("func2 end");}async function func3(next) {  console.log("func3");}async function delay() {  return new Promise((resolve, reject) => {    setTimeout(() => {      resolve();    }, 2000);  })}const middlewares = [func1, func2, func3];const finaFn = koaCompose(middlewares);finaFn()