React router dom v6 prevent transition without <Prompt>

I've learned that with react-router-dom v5 it was possible to use the <Prompt> component in order to ask the user before a page transition happens, so that the user can prevent it.

Now, for the time being, they removed it from v6 (planning to have a robust implementation "sometime later"). Instead, they recommended to implement an equivalent component by yourself ... which I would like to do now.

But: I've found no way to actually prevent the page transition in react-router-dom v6. Does anyone know anything about it?

You can but it requires using a custom history object and HistoryRouter. For this history@5 needs to be a package dependency.

1. Import version 5 of history.

   npm i -S history@5
   

2. Create and export a custom history object.

   import { createBrowserHistory } from 'history';
   
   export default createBrowserHistory();
   

3. Import and render a HistoryRouter and pass history as a prop.

   ...
   import { unstable_HistoryRouter as Router } from "react-router-dom";
   import history from './history';
   ...
   
   <Router history={history}>
     <App />
   </Router>
   

4. Follow the docs for blocking transitions.

   // Block navigation and register a callback that
   // fires when a navigation attempt is blocked.
   let unblock = history.block((tx) => {
     // Navigation was blocked! Let's show a confirmation dialog
     // so the user can decide if they actually want to navigate
     // away and discard changes they've made in the current page.
     let url = tx.location.pathname;
     if (window.confirm(`Are you sure you want to go to ${url}?`)) {
       // Unblock the navigation.
       unblock();
   
       // Retry the transition.
       tx.retry();
     }
   });
   

Demo: