IsSameType - API reference

API reference › @evolu/common › Types › IsSameType

type IsSameType<A, B> = <T>() => T extends (A & T) | T
  ? true
  : false extends <T>() => T extends (B & T) | T ? true : false
    ? [A] extends [never]
      ? [B] extends [never]
        ? true
        : false
      : [B] extends [never]
        ? false
        : true
    : false;

Defined in: packages/common/src/Types.ts:443

Returns whether two types are identical according to TypeScript.

Unlike mutual assignability, this distinguishes narrower literals, any, unknown, never, optional properties, and readonly properties. Intersection types are not normalized; apply Simplify explicitly when normalization is part of the intended comparison.

Exact type equality

import { assertType, type IsSameType } from "@evolu/common";

assertType<
  true,
  IsSameType<{ readonly id: string }, { readonly id: string }>
>();
assertType<false, IsSameType<"ready", string>>();