Primitive middleware router without timeout

middleware-router.js

// Router is a function that returns async function.
const Router = (...chain) =>
  Object.assign(
    // That async function as object have one method push()
    async (ctx) => {
      // When it calls that function it runs recursive algorithm
      return await (async function run(idx) {
        // Which calls each function in the chain
        let res = await ("AsyncFunction" !== chain[idx].constructor.name
          ? new Promise((res) => chain[idx](ctx, res))
          : chain[idx](ctx));
        // If it returns any result it will terminate chain execution
        return undefined != res
          ? res
          : idx < chain.length - 1
          ? await run(idx + 1)
          : undefined;
      })(0);
    },
    { push: (...mws) => chain.push(...mws) }
  );

// Examples of use
let router = Router();

// Each middleware is a function with 2 arguments
// first of it is context object
// second of it is callback
router.push((ctx, next) => {
  console.log(1);
  ctx.x++;
  // call of the callback pass execution to next middleware 
  next();
});

let router2 = Router();

// We can use async function as middleware
router2.push(async (ctx) => {
  console.log(2);
  ctx.x++;
});

router2.push((ctx, next) => {
  console.log(3);
  ctx.x++;
  next();
  //second call of the callback will be ignored
  setTimeout(() => next(), 1000);
});

// And we can use other router as middleware
router.push(router2);

router.push((ctx, next) => {
  console.log(4);
  ctx.x++;
  setTimeout(next, 500);
});

router.push((ctx, next) => {
  console.log(5);
  ctx.x++;
  next();
  //second call of the callback will be ignored
  next(true);
});

router.push(async (ctx) => {
  console.log(6);
  ctx.x++;
  // We can terminate chain execution 
  // if we return any other value except undefined
  return undefined;
});

router.push((ctx, next) => {
  console.log(7);
  ctx.x++;
  // terminate chain execution
  next(true);
});

// that middleware will never be called
router.push((ctx, next) => {
  console.log(8);
  ctx.x++;
  next();
});

(async () => {
  let ctx = { x: 0 };
  let res = await router(ctx);
  console.log("End");
  console.log("x=", ctx.x, "ctx=", ctx);
  console.log(res);
})();