ReactRouter v4 Prompt - override default alert

Question

The React Router v4 component is perfect for the use case of protecting navigation away from a partially filled out form.

Answer 1

Here's a component using hooks to achieve block functionality, the component didn't work for me because I wanted to ignore the search on the location.

import { useEffect, useRef } from 'react';
import { useHistory } from 'react-router-dom';

interface IProps {
    when: boolean;
    message: string;
}

export default function RouteLeavingGuard({ when, message }: IProps) {

    const history = useHistory();
    const lastPathName = useRef(history.location.pathname);

    useEffect(() => {

        const unlisten = history.listen(({ pathname }) => lastPathName.current = pathname);

        const unblock = history.block(({ pathname }) => {
            if (lastPathName.current !== pathname && when) {
                return message;
            }
        });

        return () => {
            unlisten();
            unblock();
        }
    }, [history, when, message]);

    return null;

}