assertNotUndefined - API reference

API reference › @evolu/common › Assert › assertNotUndefined

const assertNotUndefined: <T>(
  value: T,
  message?: string,
) => asserts value is T & ({} | null);

Defined in: packages/common/src/Assert.ts:394

Asserts that a value is not undefined while preserving null.

Use this when a value is logically guaranteed not to be undefined but TypeScript cannot prove it.

Example

import {
  assert,
  assertEqual,
  assertErr,
  assertNotUndefined,
  assertType,
  trySync,
} from "@evolu/common";

const value = null as string | null | undefined;
assertNotUndefined(value);
assertType<string | null, typeof value>();
assertEqual(value, null);
const result = trySync(() => assertNotUndefined(undefined));
assertErr(result);
assert(result.error instanceof Error, "Expected an Error.");
assertEqual(result.error.message, "Expected value not to be undefined.");