polkadot-js/common

// Copyright 2017-2024 @polkadot/util authors & contributors
// SPDX-License-Identifier: Apache-2.0

import type { Class } from '../types.js';

import { isClass } from './class.js';

/**
 * @name isChildClass
 * @summary Tests if the child extends the parent Class
 * @description
 * Checks to see if the child Class extends the parent Class
 * @example
 * <BR>
 *
 * ```javascript
 * import { isChildClass } from '@polkadot/util';
 *
 * console.log('isChildClass', isChildClass(BN, BN); // => true
 * console.log('isChildClass', isChildClass(BN, Uint8Array); // => false
 * ```
 */
export function isChildClass <P extends Class> (Parent: P, Child?: unknown): Child is P {
  // https://stackoverflow.com/questions/30993434/check-if-a-constructor-inherits-another-in-es6/30993664
  return isClass(Child) && isClass(Parent)
    // eslint-disable-next-line no-prototype-builtins
    ? Parent === Child || Parent.isPrototypeOf(Child)
    : false;
}