react-peekaboo

React hooks for monitoring an element's intersection with the viewport.

Installation

npm install react-peekaboo

Usage

import React, { useState } from 'react';
import { useIntersecting, useIntersectionChange } from 'react-peekaboo';

function UseIntersectionExample() {
  let [ref, isIntersecting] = useIntersecting<HTMLDivElement>();

  return (
    <div ref={ref}>I am {isIntersecting ? 'visible' : 'not visible'}.</div>
  );
}

function UseIntersectionChangeExample() {
  let [isIntersecting, onChange] = useState<boolean>(false);
  let ref = useIntersectionChange<HTMLDivElement>(onChange);

  return (
    <div ref={ref}>I am {isIntersecting ? 'visible' : 'not visible'}.</div>
  );
}

API

Options

All functions accept a common set of options:

• enabled?: boolean: Enables/disables running the side effect that calculates the element's intersection status. (default: true)

• offsetBottom?: number: Number of pixels to add to the bottom of the area checked against when computing element intersection. (default: 0)

• offsetLeft?: number: Number of pixels to add to the left of the area checked against when computing element intersection. (default: 0)

• offsetRight?: number: Number of pixels to add to the right of the area checked against when computing element intersection. (default: 0)

• offsetTop?: number: Number of pixels to add to the top of the area checked against when computing element intersection. (default: 0)

• throttle?: number: Number of ms to throttle scroll events (only applies in environments that don't support IntersectionObserver or when using useScrollIntersection/useScrollIntersectionChangeCallback). (default: 100)

Exports

useIntersecting

Type: (options: Options) => [RefCallback, boolean]

Returns a ref and the element's intersection status using IntersectionObserver or scroll/resize event listeners and getBoundingClientRect in unsupported environments.

The ref returned must be attached to a DOM node.

useIntersectionChange

Type:

(onChange: (isIntersecting: boolean) => void, options: Options) => RefCallback;

Runs a callback that receives the element's intersection status each time it changes using IntersectionObserver or scroll/resize event listeners and getBoundingClientRect in unsupported environments.

Returns a ref that must be attached to a DOM node.

usePeekaboo

Type:

type SetupHandler = (
  element: HTMLElement,
  onChange: (isIntersecting: boolean) => void,
  options?: Options,
) => TeardownHandler;

(
  setup: SetupHandler,
  onChange: (isIntersecting: boolean) => void,
  options?: Options,
) => RefCallback;

Uses setup to run onChange when the element's intersection status changes. You can pass scroll, io, or peekaboo from dom-peekaboo or implement our own setup function.