initial commit

src/index.tsx

@@ -0,0 +1,23 @@
+import React from 'react';
+import ReactDOM from 'react-dom/client';
+
+import App from './app';
+
+export default () => <App />;
+
+let rootElement: ReactDOM.Root;
+
+export const mount = (Сomponent, element = document.getElementById('app')) => {
+  const rootElement = ReactDOM.createRoot(element);
+  rootElement.render(<Сomponent />);
+
+  if (module.hot) {
+    module.hot.accept('./app', () => {
+      rootElement.render(<Сomponent />);
+    });
+  }
+};
+
+export const unmount = () => {
+  rootElement.unmount();
+};