实现中间件

[nmsn]

/*
 * 实现中间件机制
 */
function rawMethod(a) {
  return a + 1;
}

function middleware1(next) {
  return function (a) {
    return next(a) + 1;
  };
}

function middleware2(next) {
  return function (a) {
    return next(a) + 1;
  };
}

function middleware3(next) {
  return function (a) {
    return next(a) + 1;
  };
}

function applyMiddleWare(...args) {
  // 实现...
}

const newFun = applyMiddleWare(rawMethod, middleware2, middleware1);
console.log(newFun(0)); // middleware2 -> middleware1 -> rawMethod => 3

const newFun2 = applyMiddleWare(newFun, middleware3);
console.log(newFun2(0)); // middleware3 -> middleware2 -> middleware1 -> rawMethod => 4

[nmsn]

reduce 实现

迭代实现

function applyMiddleWare(...args) {

  const [raw, ...func] = args;

  return function (a) {
    let result;

    func.reverse().forEach((f, index) => {
      result = f(result || raw);
    });

    return result(a);
  };
}