#promises

TypeScriptintermediate

Awaited<T> and unwrapping nested promise types

type Nested = Promise<Promise<Promise<string>>>;
type Flat = Awaited<Nested>;

export async function loadUser(): Promise<{ id: string; name: string }> {
  return { id: "1", name: "Ada" };

Unwrap Promise<Promise<Promise<T>>> down to T in one step, the way await does at runtime, using TypeScript's built-in recursive helper.

Node.jsintermediate

events.once() to await a single event without a listener callback

import { EventEmitter, once } from "node:events";

export const waitForReady = (emitter: EventEmitter) => once(emitter, "ready");

const bus = new EventEmitter();

events.once() turns a single EventEmitter event into an awaitable promise, replacing a one-shot .on() + manual .off() with one line.