swizzle.ts

/**
 * @license
 * Copyright 2021 Google LLC
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     https://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

/* eslint @typescript-eslint/no-explicit-any: "off" */
interface Constructable<T, A extends any[]> {
  new (...args: A): T;
}

// Make an ES6 class subclassable via Backbone's extend() call.
// The primary issue here is that ES6 constructors must be invoked via 'new' but
// Backbone does not do this when creating the parent object:
// https://github.com/jashkenas/backbone/blob/153dc41616a1f2663e4a86b705fefd412ecb4a7a/backbone.js#L2060
/* eslint @typescript-eslint/no-explicit-any: "off" */
export function swizzle<T, A extends any[]>(
  base: Constructable<T, A>
): Constructable<T, A> {
  /* eslint @typescript-eslint/no-explicit-any: "off" */
  const Constructor = function (this: any, ...args: A): T {
    // ES6 new.target will be specified if being constructed via the `new`
    // keyword.
    if (new.target) {
      return Reflect.construct(base, [...args], new.target);
    }
    return Reflect.construct(base, [...args], this.constructor);
  } as unknown as Constructable<T, A>;

  Object.setPrototypeOf(Constructor.prototype, base.prototype);
  Object.setPrototypeOf(Constructor, base);

  return Constructor;
}