assertNonEmptyReadonlyArray - API reference

API reference › @evolu/common › Assert › assertNonEmptyReadonlyArray

const assertNonEmptyReadonlyArray: <T>(
  arr: ReadonlyArray<T>,
  message?: string,
) => asserts arr is NonEmptyReadonlyArray<T>;

Defined in: packages/common/src/Assert.ts:466

Asserts that a readonly array is non-empty.

Use this when a readonly array is logically guaranteed to be non-empty but TypeScript cannot prove it.

Example

import {
  assertEqual,
  assertErr,
  assertNonEmptyReadonlyArray,
  assertType,
  trySync,
  type NonEmptyReadonlyArray,
} from "@evolu/common";

const values: ReadonlyArray<number> = [1, 2, 3];
assertNonEmptyReadonlyArray(values);
assertType<NonEmptyReadonlyArray<number>, typeof values>();
assertEqual(values[0], 1);
const result = trySync(() => assertNonEmptyReadonlyArray([]));
assertErr(result);