Primitive middleware router with timeout detection

middleware-router-with-timeout-detection.js

const stepTimeout = 505;

const Router = (...chain) =>
  Object.assign(
    async (ctx) => {
      await (async function run(idx) {
        if ("function" == typeof chain[idx]) {
          await new Promise((res, rej) => {
            const to = setTimeout(
              () => rej(new Error(`Step [${idx}] timeout on \n${chain[idx]}`)),
              stepTimeout
            );
            chain[idx](ctx, () => {
              clearTimeout(to);
              res();
            });
          });
          await run(idx + 1);
        }
      })(0);
    },
    { use: (...mws) => chain.push(...mws) }
  );

let router = Router();

router.use((ctx, next) => {
  console.log(1);
  ctx.x++;
  next();
});

router.use((ctx, next) => {
  console.log(2);
  ctx.x++;
  next();
});

router.use((ctx, next) => {
  console.log(3);
  ctx.x++;
  next();
  setTimeout(() => next(), 1000);
});

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

router.use((ctx, next) => {
  console.log(5);
  ctx.x++;
  next();
  next();
});

router.use((ctx, next) => {
  console.log(6);
  ctx.x++;
  next();
});

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