@rooks/use-in-view-ref

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About

Simple hook that monitors element enters or leave the viewport that's using Intersection Observer API. It returns a ref to observed element, as well as boolean flag - inView that will tell if the element is inside of the viewport / parent element or not. You can also pass a callback that will be fired everytime the Observer will be triggered. To understand the Intersection Observer API better, please check its documentation on MDN.

Installation

npm install --save @rooks/use-in-view-ref

Importing the hook

import useInViewRef from '@rooks/use-in-view-ref';

Usage

function Demo() {
  const [myRef, inView] = useInViewRef();

  return (
    <>
      <div
        style={{
          position: 'fixed',
          top: 0,
          right: 0,
        }}
      >
        <h1>Is rectangle visible - {String(inView)}</h1>
      </div>
      <div style={{ height: 2000 }}></div>
      <div ref={myRef} style={{ height: 300, background: 'red' }}></div>
      <div style={{ height: 2000 }}></div>
    </>
  );
}

render(<Demo />);

Arguments

Argument	Type	Description	Default Value	Required
callback	IntersectionObserverCallback	Callback that will be fired when the intersection occurs	undefined	no
options	IntersectionObserverInit	Intersection Observer config (read more)	{ root: null,rootMargin: "0px 0px 0px 0px", threshold: [0, 1]}	no

Return

Returns an array with the first element in the array being the callback ref for the React component/element that needs to be observed and a second being the boolean flag that indicates if the element is in viewport.

Return value	Type	Description	Default value
ref	CallbackRef	ref for the React component/element that needs to be observed.	null
inView	boolean	flag that will indicate if the element is in viewport	false