koa-compose 简化版实现

koa-compose.js

/**
 * @function compose
 * @description compose koa middlewares
 * @param {function[]} middlewares
 * @returns {function}
 */
function compose(middlewares) {
  const done = async () => {};

  const compose = middlewares.reduce((compose, middleware) => {
    return (context, next) => {
      return compose(context, async () => {
        middleware(context, next);
      });
    };
  });

  return async (context, next = done) => {
    return compose ? compose(context, next) : next();
  };
}

PS：官方递归实现版更优，可以按需初始化！