Adds back in `useBlocker` and `usePrompt` to `react-router-dom` version 6.0.2 (they removed after the 6.0.0 beta, temporarily)

react-router-dom-v.6.02.prompt.blocker.js

/**
 * These hooks re-implement the now removed useBlocker and usePrompt hooks in 'react-router-dom'.
 * Thanks for the idea @piecyk https://github.com/remix-run/react-router/issues/8139#issuecomment-953816315
 * Source: https://github.com/remix-run/react-router/commit/256cad70d3fd4500b1abcfea66f3ee622fb90874#diff-b60f1a2d4276b2a605c05e19816634111de2e8a4186fe9dd7de8e344b65ed4d3L344-L381
 */
import { useContext, useEffect, useCallback } from 'react';
import { UNSAFE_NavigationContext as NavigationContext } from 'react-router-dom';
/**
 * Blocks all navigation attempts. This is useful for preventing the page from
 * changing until some condition is met, like saving form data.
 *
 * @param  blocker
 * @param  when
 * @see https://reactrouter.com/api/useBlocker
 */
export function useBlocker( blocker, when = true ) {
	const { navigator } = useContext( NavigationContext );

	useEffect( () => {
		if ( ! when ) return;

		const unblock = navigator.block( ( tx ) => {
			const autoUnblockingTx = {
				...tx,
				retry() {
					// Automatically unblock the transition so it can play all the way
					// through before retrying it. TODO: Figure out how to re-enable
					// this block if the transition is cancelled for some reason.
					unblock();
					tx.retry();
				},
			};

			blocker( autoUnblockingTx );
		} );

		return unblock;
	}, [ navigator, blocker, when ] );
}
/**
 * Prompts the user with an Alert before they leave the current screen.
 *
 * @param  message
 * @param  when
 */
export function usePrompt( message, when = true ) {
	const blocker = useCallback(
		( tx ) => {
			// eslint-disable-next-line no-alert
			if ( window.confirm( message ) ) tx.retry();
		},
		[ message ]
	);

	useBlocker( blocker, when );
}

usage.useprompt.react-router-dom.js

const MyComponent = () => {
	const formIsDirty = true; // Condition to trigger the prompt.
	usePrompt( 'Leave screen?', formIsDirty );
	return (
		<div>Hello world</div> 
	);
};

Here's a useBeforeUnload hook for v6.4.3 that catches both react router navigation and browser navigation:

import { useCallback } from 'react';
import { useBeforeUnload as _useBeforeUnload, unstable_usePrompt as usePrompt } from 'react-router-dom';

export default function useBeforeUnload(doBlock?: boolean) {
  _useBeforeUnload(
    useCallback(e => {
      if (doBlock) {
        e.preventDefault();
        return e.returnValue = '';
      }
    }, [doBlock])
  );

  usePrompt({
    when: doBlock,
    message: 'Discard unsaved changes?'
  });
}

This is awesome, thanks for sharing! 💯

you can simply add these:

useEffect(() => {
   window.addEventListener("beforeunload", onBeforeUnload);
   return () => {
     window.removeEventListener("beforeunload", onBeforeUnload);
   };
 });

 const onBeforeUnload = (e) => {
   if (hasDirty) {
     e.preventDefault();
     e.returnValue = "";
   }
 };

Reference : https://claritydev.net/blog/display-warning-for-unsaved-form-data-on-page-exit

you can simply add these:

useEffect(() => {
   window.addEventListener("beforeunload", onBeforeUnload);
   return () => {
     window.removeEventListener("beforeunload", onBeforeUnload);
   };
 });

 const onBeforeUnload = (e) => {
   if (hasDirty) {
     e.preventDefault();
     e.returnValue = "";
   }
 };

Reference : https://claritydev.net/blog/display-warning-for-unsaved-form-data-on-page-exit

This doesn't fire during route transitions...