Update react, use Typescript

babel.config.js

@@ -15,7 +15,5 @@
  */
 
 module.exports = {
-  presets: [
-    "@babel/preset-env"
-  ]
+  presets: ["@babel/preset-env", "@babel/preset-typescript"],
 };

hardware-concurrency/hardware-concurrency.test.ts

@@ -0,0 +1,68 @@
+/**
+ * @jest-environment jsdom
+ */
+
+import { describe, expect, test, afterEach, jest } from "@jest/globals";
+import { renderHook } from "@testing-library/react";
+
+afterEach(function () {
+  // Reload hook for every test
+  jest.resetModules();
+});
+
+describe("useHardwareConcurrency", () => {
+  const navigator = window.navigator;
+
+  afterEach(() => {
+    if (!window.navigator) window.navigator = navigator;
+  });
+
+  test(`should return "true" for unsupported case`, () => {
+    Object.defineProperty(window, "navigator", {
+      value: undefined,
+      configurable: true,
+      writable: true,
+    });
+
+    const { useHardwareConcurrency } = require(".");
+    const { result } = renderHook(() => useHardwareConcurrency());
+
+    expect(result.current.unsupported).toBe(true);
+  });
+
+  test(`should return window.navigator.hardwareConcurrency`, () => {
+    const { useHardwareConcurrency } = require(".");
+    const { result } = renderHook(() => useHardwareConcurrency());
+
+    expect(result.current.numberOfLogicalProcessors).toBe(
+      window.navigator.hardwareConcurrency
+    );
+    expect(result.current.unsupported).toBe(false);
+  });
+
+  test("should return 4 for device of hardwareConcurrency = 4", () => {
+    Object.defineProperty(window.navigator, "hardwareConcurrency", {
+      value: 4,
+      configurable: true,
+      writable: true,
+    });
+    const { useHardwareConcurrency } = require(".");
+    const { result } = renderHook(() => useHardwareConcurrency());
+
+    expect(result.current.numberOfLogicalProcessors).toEqual(4);
+    expect(result.current.unsupported).toBe(false);
+  });
+
+  test("should return 2 for device of hardwareConcurrency = 2", () => {
+    Object.defineProperty(window.navigator, "hardwareConcurrency", {
+      value: 2,
+      configurable: true,
+      writable: true,
+    });
+    const { useHardwareConcurrency } = require(".");
+    const { result } = renderHook(() => useHardwareConcurrency());
+
+    expect(result.current.numberOfLogicalProcessors).toEqual(2);
+    expect(result.current.unsupported).toBe(false);
+  });
+});

hardware-concurrency/hardware-concurrency.ts

@@ -0,0 +1,17 @@
+let initialHardwareConcurrency: {
+  unsupported: boolean;
+  numberOfLogicalProcessors?: number;
+};
+if (typeof navigator !== 'undefined' && 'hardwareConcurrency' in navigator) {
+  initialHardwareConcurrency = {
+    unsupported: false,
+    numberOfLogicalProcessors: navigator.hardwareConcurrency,
+  };
+} else {
+  initialHardwareConcurrency = { unsupported: true };
+}
+const useHardwareConcurrency = () => {
+  return { ...initialHardwareConcurrency };
+};
+
+export { useHardwareConcurrency };

hardware-concurrency/index.ts

@@ -0,0 +1 @@
+export { useHardwareConcurrency } from './hardware-concurrency';

media-capabilities/index.ts

@@ -0,0 +1 @@
+export { useMediaCapabilitiesDecodingInfo } from './media-capabilities';