Determine if ellipsis is showing for text truncated with -webkit-line-clamp

Question

I have a paragraph tag I am wanting to check if the ellipsis is showing, but I am using the -webkit-line-clamp css property.

I have the following component and hook, however using width values doesn't work. The values for scrollWidth, clientWidth and offsetWidth are always the same value.

const Description = ({ data }: Props) => {
  const [open, setOpen] = useState<boolean>(false);
  const ref = useRef<HTMLParagraphElement>(null);
  const isTruncated = useIsTruncated(ref);

  return (
    <>
      <div className="my-3 max-h-[4.5rem] relative">
        <p ref={ref} className="inline line-clamp-3">
          {data.description}
        </p>
        {isTruncated && (
          <button
            className="text-blue-600 leading-none absolute bottom-0 right-0 font-medium"
            onClick={() => setOpen(true)}
          >
            more
          </button>
        )}
      </div>
      <Modal open={open} setOpen={setOpen} />
    </>
  );
};


const useIsTruncated = (element: RefObject<HTMLParagraphElement>) => {
  const determineIsTruncated = () => {
    if (!element.current) return false;
    return element.current.scrollWidth > element.current.clientWidth;
  };
  const [isTruncated, setIsTruncated] = useState(determineIsTruncated());

  useEffect(() => {
    const resizeListener = () => setIsTruncated(determineIsTruncated());
    window.addEventListener("resize", resizeListener);
    return () => {
      window.removeEventListener("resize", resizeListener);
    };
  }, []);
  return isTruncated;
};

Is this possible using -webkit-line-clamp?

---

I am using tailwindcss, the css for line-clamp-3 is:

overflow: hidden;
display: -webkit-box;
-webkit-box-orient: vertical;
-webkit-line-clamp: 3;

Answer 1

So the trick with this was to check the height, not width.

const determineIsTruncated = () => {
  if (!element.current) return false;
  return element.current.scrollHeight > element.current.clientHeight;
};