Polyfill Array copying methods (#59091)

Summary:

Install guarded `Array.prototype.toSorted` and `Array.prototype.toReversed` polyfills during default React Native environment setup. Both methods return shallow copies and preserve native implementations when the runtime already provides them.

Register the language polyfills alongside the existing Promise setup rather than coupling them to the generic global-variable setup.

Changelog:
[General][Added] - Polyfill `Array.prototype.toSorted` and `Array.prototype.toReversed` when the JavaScript runtime does not provide them

Differential Revision: D125283374

Author: javache

packages/react-native/Libraries/Core/__tests__/polyfillArrayES2023Methods-itest.js

@@ -0,0 +1,48 @@
+/**
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ *
+ * @flow strict-local
+ * @format
+ * @fantom_hermes_variant *
+ */
+
+'use strict';
+
+const originalToSorted = Array.prototype.toSorted;
+const originalToReversed = Array.prototype.toReversed;
+
+require('@react-native/fantom/src/setUpDefaultReactNativeEnvironment');
+
+describe('Array ES2023 method polyfills', () => {
+  it('preserves native methods and fills missing methods', () => {
+    if (originalToSorted == null) {
+      expect(Array.prototype.toSorted).toBeDefined();
+    } else {
+      expect(Array.prototype.toSorted).toBe(originalToSorted);
+    }
+
+    if (originalToReversed == null) {
+      expect(Array.prototype.toReversed).toBeDefined();
+    } else {
+      expect(Array.prototype.toReversed).toBe(originalToReversed);
+    }
+  });
+
+  it('provides non-mutating copying behavior', () => {
+    const input = [3, 1, 2];
+
+    expect(input.toSorted((a, b) => a - b)).toEqual([1, 2, 3]);
+    expect(input.toReversed()).toEqual([2, 1, 3]);
+    expect(input).toEqual([3, 1, 2]);
+    expect(
+      Object.getOwnPropertyDescriptor(Array.prototype, 'toSorted')?.enumerable,
+    ).toBe(false);
+    expect(
+      Object.getOwnPropertyDescriptor(Array.prototype, 'toReversed')
+        ?.enumerable,
+    ).toBe(false);
+  });
+});

packages/react-native/Libraries/Core/polyfillArrayES2023Methods.js

@@ -0,0 +1,40 @@
+/**
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ *
+ * @flow strict
+ * @format
+ */
+
+'use strict';
+
+const arrayPrototype = Array.prototype;
+
+if (arrayPrototype.toSorted == null) {
+  Object.defineProperty(arrayPrototype, 'toSorted' as string, {
+    configurable: true,
+    value: function <T>(
+      this: Array<T>,
+      compareFn?: (a: T, b: T) => number,
+    ): Array<T> {
+      const copy = Array.from(this);
+      copy.sort(compareFn);
+      return copy;
+    },
+    writable: true,
+  });
+}
+
+if (arrayPrototype.toReversed == null) {
+  Object.defineProperty(arrayPrototype, 'toReversed' as string, {
+    configurable: true,
+    value: function <T>(this: Array<T>): Array<T> {
+      const copy = Array.from(this);
+      copy.reverse();
+      return copy;
+    },
+    writable: true,
+  });
+}

packages/react-native/src/private/setup/setUpDefaultReactNativeEnvironment.js

@@ -23,6 +23,7 @@ export default function setUpDefaultReactNativeEnvironment(
   require('./setUpDOM').default();
   require('./setUpPerformance').default();
   require('../../../Libraries/Core/polyfillPromise');
+  require('../../../Libraries/Core/polyfillArrayES2023Methods');
   require('../../../Libraries/Core/setUpTimers');
   if (__DEV__ && enableDeveloperTools) {
     require('../../../Libraries/Core/setUpReactDevTools');