create your own tRPC-like api with JavaScript proxy and a little bit of ts magic

generic-proxy.ts

const setProxySettings = (
  {
    call,
    filter,
  }: {
    call: ({ path, args }: { path: unknown; args: unknown[] }) => any;
    filter: (path: string[]) => unknown;
  } = {
    call: ({ path, args }) => {
      return {
        path,
        args,
      };
    },
    filter: (path: string[]) => path,
  }
) => {
  const createProxyClient = <T,>(path: string[] = []) => {
    const proxy = new Proxy(() => {}, {
      get(_, key: string) {
        if (typeof key !== "string" || key === "then" || key === "toJSON") {
          // special case for if the proxy is accidentally treated
          // like a PromiseLike (like in `Promise.resolve(proxy)`)
          return undefined;
        }
        return createProxyClient([...path, key]);
      },
      apply(_1, _2, args) {
        const filteredPath = filter(path);
        return call({
          path: filteredPath,
          args,
        });
      },
    }) as unknown as T;

    return proxy;
  };

  return createProxyClient;
};
const createProxyClient = setProxySettings({
  call: ({ path, args }) => {
    console.log("call", { path, args });
    return {
      path,
      args,
    };
  },
  filter: (path) => path,
});
// @ts-ignore
const createClient = <T,>() => createProxyClient<T>() as T;

const obj = {
  foo: (param: string) => "str",
  nested: {
    some: (k: string) => "foo",
  },
};
const p = createClient<typeof obj>();

p.nested.some("fsd");
// logs:
// "call",  {
//   "path": [
//     "nested",
//     "some"
//   ],
//   "args": [
//     "fsd"
//   ]
// }