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src/index.tsx

@@ -1,13 +1,15 @@
-import React from "react";
-import ReactDom from "react-dom";
-
-import App from "./app";
+import React from 'react';
+import ReactDOM from 'react-dom/client';
+  
+import App from './app';
 import { keycloak } from "./__data__/kc";
 import { createStore } from "./__data__/store";
 
 export default (props) => <App {...props} />;
-
-export const mount = async (Сomponent) => {
+  
+let rootElement: ReactDOM.Root
+  
+export const mount = async (Сomponent, element = document.getElementById('app')) => {
   let user = null;
   try {
     await keycloak.init({ onLoad: "login-required" }); // 'login-required' });
@@ -18,15 +20,16 @@ export const mount = async (Сomponent) => {
   }
   const store = createStore({ user });
 
-  ReactDom.render(<Сomponent store={store} />, document.getElementById("app"));
+  const rootElement = ReactDOM.createRoot(element);
+  rootElement.render(<Сomponent store={store} />);
 
-  if (module.hot) {
-    module.hot.accept("./app", () => {
-      ReactDom.render(<App store={store} />, document.getElementById("app"));
-    });
+  if(module.hot) {
+      module.hot.accept('./app', ()=> {
+        rootElement.render(<Сomponent store={store} />);
+      })
   }
 };
 
 export const unmount = () => {
-  ReactDom.unmountComponentAtNode(document.getElementById("app"));
+  rootElement.unmount();
 };