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The Deno Standard Library
function assertType
import { assertType } from "";

Asserts at compile time that the provided type argument's type resolves to the expected boolean literal type.


Example 1

import { assertType, IsExact, IsNullable } from "";

const result = "some result" as string | number;

// compile error if the type of `result` is not exactly `string | number`
assertType<IsExact<typeof result, string | number>>(true);

// causes a compile error that `true` is not assignable to `false`
assertType<IsNullable<string>>(true); // error: string is not nullable

Type Parameters

T extends true | false


_expectTrue: T
  • True if the passed in type argument resolved to true.