Remove event listener manually react hooks

Question

I have a scroll event listener and I want to remove it based on page URL, how can I handle it using in a hook component?

 useEffect(() => {
    function handleScrollEvent() {
      if (window.scrollY > 100) {
        setHeaderIsVisible(true);
      } else {
        setHeaderIsVisible(false);
      }
    }
    if (props.location.pathname === "/") {

      window.addEventListener("scroll", handleScrollEvent, true);
    } else {
      window.removeEventListener("scroll", handleScrollEvent, true);
    }
  }, [props.location.pathname]);

Where I should define the handleScrollEvent to remove it from listener?

Answer 1

What you need to do is every time you add it, you also remove it.

When props.location.pathname changes, it will remove the event listener.

useEffect(() => {
    if (props.location.pathname === "/") {  
      function handleScrollEvent() {
        if (window.scrollY > 100) {
          setHeaderIsVisible(true);
        } else {
          setHeaderIsVisible(false);
        }
      }

      window.addEventListener("scroll", handleScrollEvent, true);  
      // every time you add it, you also remove it when props.location.pathname changes
      return () => {
           window.removeEventListener("scroll", handleScrollEvent, true);
      }
    }
  }, [props.location.pathname]);