To help you get started, we've collected the most common ways that react-intersection-observer is being used within popular public projects.

maapteh / graphql-modules-app / packages / app / src / modules / product / product.spec.tsx View on Github

it('renders correctly', async () => {
        const id = '9200000111963040';
        const testId = 'product-details';

        const { container, queryByTestId, findByText } = render(
            
                
            
        );

        mockAllIsIntersecting(true);

        expect(queryByTestId(testId)).toBe(null);
        await findByText(/De Ghost Recon/);
        expect(queryByTestId(testId)).toBeDefined();

        // generic contract
        expect(container).toMatchSnapshot();
    });
});

View more ways to use react-intersection-observer

react-intersection-observer

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React implementation of the Intersection Observer API to tell you when an element enters or leaves the viewport. Contains both a Hooks, render props and plain children implementation.

Features

• 🪝 Hooks or Component API - With useInView it's easier than ever to monitor elements
• ⚡️ Optimized performance - Reuses Intersection Observer instances where possible
• ⚙️ Matches native API - Intuitive to use
• 🛠 Written in TypeScript - It'll fit right into your existing TypeScript project
• 🧪 Ready to test - Mocks the Intersection Observer for easy testing with Jest or Vitest
• 🌳 Tree-shakeable - Only include the parts you use
• 💥 Tiny bundle - Around ~1.15kB for useInView and ~1.6kB for ``

Installation

Install the package with your package manager of choice:

npm install react-intersection-observer --save

Usage

useInView hook

// Use object destructuring, so you don't need to remember the exact order
const { ref, inView, entry } = useInView(options);

// Or array destructuring, making it easy to customize the field names
const [ref, inView, entry] = useInView(options);

The useInView hook makes it easy to monitor the inView state of your components. Call the useInView hook with the (optional) options you need. It will return an array containing a ref, the inView status and the current entry. Assign the ref to the DOM element you want to monitor, and the hook will report the status.

import React from "react";
import { useInView } from "react-intersection-observer";

const Component = () => {
  const { ref, inView, entry } = useInView({
    /* Optional options */
    threshold: 0,
  });

  return (
    <div>
      <h2>{`Header inside viewport ${inView}.`}</h2>
    </div>
  );
};

Render props

To use the `` component, you pass it a function. It will be called whenever the state changes, with the new value of inView. In addition to the inView prop, children also receive a ref that should be set on the containing DOM element. This is the element that the Intersection Observer will monitor.

If you need it, you can also access the IntersectionObserverEntry on entry, giving you access to all the details about the current intersection state.

import { InView } from "react-intersection-observer";

const Component = () => (
  
    {({ inView, ref, entry }) => (
      <div>
        <h2>{`Header inside viewport ${inView}.`}</h2>
      </div>
    )}
  
);

export default Component;

Plain children

You can pass any element to the , and it will handle creating the wrapping DOM element. Add a handler to the `onChange` method, and control the state in your own component. Any extra props you add to will be passed to the HTML element, allowing you set the className, style, etc.

import { InView } from "react-intersection-observer";

const Component = () => (
   console.log("Inview:", inView)}>
    <h2>Plain children are always rendered. Use onChange to monitor state.</h2>
  
);

export default Component;

> [!NOTE] > When rendering a plain child, make sure you keep your HTML output > semantic. Change the as to match the context, and add a className to style > the ``. The component does not support Ref Forwarding, so if you > need a ref to the HTML element, use the Render Props version instead.

API

Options

Provide these as the options argument in the useInView hook or as props on the `` component.

InView Props

The `` component also accepts the following props:

Intersection Observer v2 🧪

The new v2 implementation of IntersectionObserver extends the original API, so you can track if the element is covered by another element or has filters applied to it. Useful for blocking clickjacking attempts or tracking ad exposure.

To use it, you'll need to add the new trackVisibility and delay options. When you get the entry back, you can then monitor if isVisible is true.

const TrackVisible = () => {
  const { ref, entry } = useInView({ trackVisibility: true, delay: 100 });
  return <div>{entry?.isVisible}</div>;
};

This is still a very new addition, so check caniuse for current browser support. If trackVisibility has been set, and the current browser doesn't support it, a fallback has been added to always report isVisible as true.

It's not added to the TypeScript lib.d.ts file yet, so you will also have to extend the IntersectionObserverEntry with the isVisible boolean.

Recipes

The IntersectionObserver itself is just a simple but powerful tool. Here's a few ideas for how you can use it.

• Lazy image load
• Trigger animations
• Track impressions (Google Analytics, Tag Manager, etc.)

FAQ

How can I assign multiple refs to a component?

You can wrap multiple ref assignments in a single useCallback:

import React, { useRef, useCallback } from "react";
import { useInView } from "react-intersection-observer";

function Component(props) {
  const ref = useRef();
  const { ref: inViewRef, inView } = useInView();

  // Use `useCallback` so we don't recreate the function on each render
  const setRefs = useCallback(
    (node) => {
      // Ref's from useRef needs to have the node assigned to `current`
      ref.current = node;
      // Callback refs, like the one from `useInView`, is a function that takes the node as an argument
      inViewRef(node);
    },
    [inViewRef],
  );

  return <div>Shared ref is visible: {inView}</div>;
}

rootMargin isn't working as expected

When using rootMargin, the margin gets added to the current root - If your application is running inside a `