react-inview-hook

react-hooks with intersection-observer.

Why?

This module will cache IntersectionObservers (group by IntersectionObserverInit).

That's reason is performance on IE11 with polyfill.

Note

This module uses Map and IntersectionObserver If you use this in es5 environment, should install polyfills below.

• Map
  • @babel/polyfill or es6-map etc.
• IntersectionObserver
  • intersection-observer

Usage

import React, { useState, useRef } from "react";
import { useInView } from "react-inview-hook";
 
export const SomeComponent = () => {
  const [isInView, setIsInView] = useState(false);
  const ref = useRef(null);
 
  useInView({
    ref,
    onEnter: () => setIsInView(true),
    onLeave: () => setIsInView(false)
  });
 
  return <div ref={ref}>isInView? {isInView ? "true" : "false"}</div>;
};

API

useInView(props: UseInViewProps)

type UseInViewProps = {
  ref: React.RefObject<Element>;
 
  onEnter?: (entry: IntersectionObserverEntry) => void;
 
  onLeave?: (entry: IntersectionObserverEntry) => void;
 
  unobserveOnEnter?: boolean; // default: false
 
  root?: React.RefObject<Element>; // default: null
 
  rootMargin?: string; // default: '0px'
 
  threshold?: number | number[]; // default: 0
};