return `usePrompt` capabilities from react-router

use-prompt.ts

/**
 * Prompts a user when they exit the page
 */

import { useCallback, useContext, useEffect } from 'react';
import { UNSAFE_NavigationContext as NavigationContext } from 'react-router-dom';

function useConfirmExit(confirmExit: () => boolean, when = true) {
  const { navigator } = useContext(NavigationContext);

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

    const push = navigator.push;

    navigator.push = (...args: Parameters<typeof push>) => {
      const result = confirmExit();
      if (result !== false) {
        push(...args);
      }
    };

    return () => {
      navigator.push = push;
    };
  }, [navigator, confirmExit, when]);
}

export function usePrompt(message: string, when = true) {
  useEffect(() => {
    if (when) {
      window.onbeforeunload = function () {
        return message;
      };
    }

    return () => {
      window.onbeforeunload = null;
    };
  }, [message, when]);

  const confirmExit = useCallback(() => {
    const confirm = window.confirm(message);
    return confirm;
  }, [message]);
  useConfirmExit(confirmExit, when);
}

your example wont work because cant import unstable_useBlocker from the router.

@yara-tle yeah this example was written while it was unstable API. Now you can import useBlocker without unstable prefix

@denchiklut useBlocker and usePrompt don't work with routers that don't have access to the new data API, like BrowserRouter component, this gist does

hey, do you manage to block when the user clicks the back browser button?

for anyone having issue with the back button, check this code

import { useCallback, useContext, useEffect } from "react";
import { useDispatch } from "react-redux";
import { UNSAFE_NavigationContext as NavigationContext } from "react-router-dom";

function useConfirmExit(confirmExit: () => boolean, when = true) {
  const { navigator } = useContext(NavigationContext);

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

    const push = navigator.push;

    navigator.push = (...args: Parameters<typeof push>) => {
      const result = confirmExit();

      if (result !== false) {
        push(...args);
      }
    };

    return () => {
      navigator.push = push;
    };
  }, [navigator, confirmExit, when]);
}

export function usePrompt(message: string, when = true) {
  useEffect(() => {
    if (!when) return;
    window.onbeforeunload = function () {
      return message;
    };

    window.history.pushState(null, "", window.location.href);
    window.onpopstate = function () {
      const confirm = window.confirm(message);

      if (confirm) {
        dispatch(setIsEditing(false));
        window.onpopstate = null;
        window.history.back();
      } else {
        window.history.pushState(null, "", window.location.href);
      }
    };
    return () => {
      window.onbeforeunload = null;
      window.onpopstate = null;
      }, [message, when]);

  const confirmExit = useCallback(() => {
    const confirm = window.confirm(message);

    if (confirm) {
      dispatch(setIsEditing(false));
    }

    return confirm;
  }, [message]);
  useConfirmExit(confirmExit, when);
}

for anyone having issue with the back button, check this code

import { useCallback, useContext, useEffect } from "react";
import { useDispatch } from "react-redux";
import { UNSAFE_NavigationContext as NavigationContext } from "react-router-dom";

function useConfirmExit(confirmExit: () => boolean, when = true) {
  const { navigator } = useContext(NavigationContext);

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

    const push = navigator.push;

    navigator.push = (...args: Parameters<typeof push>) => {
      const result = confirmExit();

      if (result !== false) {
        push(...args);
      }
    };

    return () => {
      navigator.push = push;
    };
  }, [navigator, confirmExit, when]);
}

export function usePrompt(message: string, when = true) {
  useEffect(() => {
    if (!when) return;
    window.onbeforeunload = function () {
      return message;
    };

    window.history.pushState(null, "", window.location.href);
    window.onpopstate = function () {
      const confirm = window.confirm(message);

      if (confirm) {
        dispatch(setIsEditing(false));
        window.onpopstate = null;
        window.history.back();
      } else {
        window.history.pushState(null, "", window.location.href);
      }
    };
    return () => {
      window.onbeforeunload = null;
      window.onpopstate = null;
      }, [message, when]);

  const confirmExit = useCallback(() => {
    const confirm = window.confirm(message);

    if (confirm) {
      dispatch(setIsEditing(false));
    }

    return confirm;
  }, [message]);
  useConfirmExit(confirmExit, when);
}

Thanks for the suggestion, @kanavi57

This code works when the user clicks directly on the back button, but it won't work if the user long-presses the back button and chooses a specific page to return to.