use-location.js

import { useEffect, useRef, useState, useCallback } from "./react-deps.js";

/**
 * History API docs @see https://developer.mozilla.org/en-US/docs/Web/API/History
 */
const eventPopstate = "popstate";
const eventPushState = "pushState";
const eventReplaceState = "replaceState";
export const events = [eventPopstate, eventPushState, eventReplaceState];

export default ({ base = "" } = {}) => {
  const [{ path, search }, update] = useState(() => ({
    path: currentPathname(base),
    search: location.search,
  })); // @see https://reactjs.org/docs/hooks-reference.html#lazy-initial-state
  const prevHash = useRef(path + search);

  useEffect(() => {
    // this function checks if the location has been changed since the
    // last render and updates the state only when needed.
    // unfortunately, we can't rely on `path` value here, since it can be stale,
    // that's why we store the last pathname in a ref.
    const checkForUpdates = () => {
      const pathname = currentPathname(base);
      const search = location.search;
      const hash = pathname + search;

      if (prevHash.current !== hash) {
        prevHash.current = hash;
        update({ path: pathname, search });
      }
    };

    events.forEach((e) => addEventListener(e, checkForUpdates));

    // it's possible that an update has occurred between render and the effect handler,
    // so we run additional check on mount to catch these updates. Based on:
    // https://gist.github.com/bvaughn/e25397f70e8c65b0ae0d7c90b731b189
    checkForUpdates();

    return () => events.forEach((e) => removeEventListener(e, checkForUpdates));
  }, [base]);

  // the 2nd argument of the `useLocation` return value is a function
  // that allows to perform a navigation.
  //
  // the function reference should stay the same between re-renders, so that
  // it can be passed down as an element prop without any performance concerns.
  const navigate = useCallback(
    (to, { replace = false } = {}) =>
      history[replace ? eventReplaceState : eventPushState](
        null,
        "",
        // handle nested routers and absolute paths
        to[0] === "~" ? to.slice(1) : base + to
      ),
    [base]
  );

  return [path, navigate];
};

// While History API does have `popstate` event, the only
// proper way to listen to changes via `push/replaceState`
// is to monkey-patch these methods.
//
// See https://stackoverflow.com/a/4585031
if (typeof history !== "undefined") {
  for (const type of [eventPushState, eventReplaceState]) {
    const original = history[type];

    history[type] = function () {
      const result = original.apply(this, arguments);
      const event = new Event(type);
      event.arguments = arguments;

      dispatchEvent(event);
      return result;
    };
  }
}

const currentPathname = (base, path = location.pathname) =>
  !path.toLowerCase().indexOf(base.toLowerCase())
    ? path.slice(base.length) || "/"
    : "~" + path;