I am trying to save a session key when user leaves the page here is the code for it, The use of the code is upon loading a page, you want to:

If this page was the last visited page: load its saved location else remove the last saved location and save it upon scrolling.

 const [scrollPosition, setScrollPosition] = React.useState('');

React.useEffect(() => {
    var pathName = document.location.pathname.substr(1);
    if (window) {
      window.onscroll = function (e) {
        setScrollPosition(window.scrollY);
      };
    }
  }, [scrollPosition]);

  if (typeof window !== "undefined") {
    window.addEventListener('unload', function(event) {
      if(scrollPosition != 0){
        const savedPosition = { position: scrollPosition, pathName };
        sessionStorage.setItem('scrollPosition', JSON.stringify(savedPosition));
      }
    }); 
  }

  React.useEffect(() => {
    var pathName = document.location.pathname.substr(1);
    const lastSavedPosition = JSON.parse(sessionStorage.getItem('scrollPosition'));
    if (window && lastSavedPosition && pathName === lastSavedPosition.pathName) {
       window.scrollTo(0, lastSavedPosition.position);
      console.log(`position_set to = ${lastSavedPosition.position}`);
    }
  }, []);