Simple Http Router Using JS Proxy Hack

router.ts

export type TRouter<Value, Method extends string> =
  & {
    find: (method: Method, pathname: string) => TMatchedRoute<Value>;
  }
  & {
    [k in Lowercase<Method>]: (
      pathname: string,
      ...values: Value[]
    ) => TRouter<Value, Method>;
  };

type TRoute<H, Method> = [Method, URLPattern, H[]];

type TMatchedRoute<Value> =
  | (URLPatternComponentResult & { handlers: Value[] })
  | undefined;

export function createRouter<
  Value = never,
  Method extends string = "ALL" | "GET" | "POST" | "PUT" | "PATCH" | "DELETE",
>(
  init: [Method, string, Value[]][] = [],
) {
  const add = (
      ...[method, pathname, handlers]: typeof init[number]
    ): TRoute<Value, Method> => [
      method,
      new URLPattern({ pathname }),
      handlers,
    ],
    routes: TRoute<Value, Method>[] = init.length > 0
      ? [...init.map((i) => add(...i))]
      : [],
    find = (
      method: Method,
      pathname: string,
    ): TMatchedRoute<Value> => {
      let result: TMatchedRoute<Value>;
      for (const [rmethod, pattern, handlers] of routes) {
        if (method === rmethod || "ALL" === rmethod) {
          const match = pattern.exec({ pathname })?.pathname;
          if (match) {
            if (result) {
              result.handlers.push(...handlers);
            } else {
              result = { ...match, handlers };
            }
          }
        }
      }
      return result;
    },
    get = (
      _: never,
      prop: string,
      receiver: never,
    ) => ("find" === prop
      ? find
      : (pathname: string, ...handlers: Value[]) =>
        routes.push(add(prop as never, pathname, handlers)) && receiver);
  return new Proxy({}, { get }) as never as TRouter<Value, Method>;
}

test.ts

// deno-lint-ignore-file
import { createRouter } from "./router.ts";

// deno-lint-ignore-file no-explicit-any
type RHandler = (
  req: Request,
  params: Record<string, string | number>,
) => Response | Promise<Response> | void | Promise<void>;
const router = createRouter<RHandler>([
  // Initial
  ["GET", "/", [
    () => {
      console.log("Step 1");
    },
    async () => {
      console.log("Step 2");
    },
    async () => {
      return new Response("Holaaaa")
    },
    () => {
      console.log("Not Called");
    },
  ]],
]);

// you can do
router.get("/:hello", (req, params) => new Response("Hello "+params.hello))

// sample request resolver
const resolveRouterResult = async (req: Request) => {
  const { pathname } = new URL(req.url);
  const result = router.find(req.method as never, pathname);
  if (result) {
    for (const handler of result.handlers) {
      let res = await handler(req, result.groups)
      if (res !== undefined) {
        console.log(await res.text());
        break;
      }
    }
  } else {
    throw new Error("No route are found!");
  }
};

await resolveRouterResult(new Request("https://arisris.com"));