isPromiseLike - API reference

API reference › @evolu/common › Types › isPromiseLike

function isPromiseLike<T>(value: Awaitable<T>): value is PromiseLike<T>;

Defined in: packages/common/src/Types.ts:412

Type guard to check if a value is a PromiseLike.

Use with Awaitable to conditionally await only when necessary, avoiding microtask overhead for synchronous values.

Conditional awaiting

import { assertTrue, isPromiseLike, type Awaitable } from "@evolu/common";

const cache = new Map([["cached", true]]);
const validate = (id: string): Awaitable<boolean> =>
  cache.get(id) ?? Promise.resolve(false);

const result = validate("cached");
const isValid = isPromiseLike(result) ? await result : result;

assertTrue(isValid);