std/assert/assert_exists.ts

19 lines
544 B
TypeScript

// Copyright 2018-2023 the Deno authors. All rights reserved. MIT license.
import { AssertionError } from "./assertion_error.ts";
/**
* Make an assertion that actual is not null or undefined.
* If not then throw.
*/
export function assertExists<T>(
actual: T,
msg?: string,
): asserts actual is NonNullable<T> {
if (actual === undefined || actual === null) {
const msgSuffix = msg ? `: ${msg}` : ".";
msg =
`Expected actual: "${actual}" to not be null or undefined${msgSuffix}`;
throw new AssertionError(msg);
}
}