useIntersectionObserver

Usage#

import { useIntersectionObserver } from '@primereact/hooks/use-intersection-observer';

const ref = React.useRef<HTMLDivElement>(null);
const { observe, isIntersecting } = useIntersectionObserver({
    threshold: 0.5,
    onIntersect: (entries) => console.log(entries)
});
 
React.useEffect(() => {
    if (ref.current) observe(ref.current);
}, [observe]);
 
return <div ref={ref}>{isIntersecting ? 'visible' : 'off-screen'}</div>;

Options#

Standard IntersectionObserverInit fields (root, rootMargin, threshold) plus:

• disabled? — skip creating the observer entirely.
• onIntersect?(entries, observer) — called on every intersection change.
• fallback?() — invoked when IntersectionObserver is unavailable.

Returns#

• entries — current entries from the last callback.
• isIntersecting — true if any observed element is intersecting.
• observe(el), unobserve(el), disconnect() — imperative controls.
• observer — the underlying IntersectionObserver instance (or null when disabled).

When to use it#

Pick this hook when you need direct control — observing multiple elements, toggling dynamically, or integrating with virtualization. For simple "is this one element visible" cases, you may prefer the lighter-weight visibility patterns built on top of it.