useScrollSpy

Automatically update navigation based on scroll position.

Installation

Install the custom hook from your command line.

npm i @raddix/use-scroll-spy

Usage

import { useScrollSpy } from '@raddix/use-scroll-spy';

export default function TableOfContent() {
  const headings = [
    {id: 'overview', text: 'Overview'},
    {id: 'components', text: 'Creating and nesting components '},
    {id: 'styles', text: 'Adding styles'},
  ]
  const headingIds = headings.map(({id}) => id)

  const activeId = useScrollSpy(headingIds, {
      rootMargin: "0% 0% -80% 0%",
  });

  return (
    <ul>
      {headings.map((heading, i) => (
          <li
            key={i}
            style={
              activeId === heading.id ? { color: 'blue' } : { color: '#000' }
            }
          >
            <a href={`#${heading.id}`}>{heading.text}</a>
          </li>
        ))}
    </ul>
  );
};

API

Behind the scenes, it uses the Intersection Observer Web API, so you can rely on the best performance standards while not having to worry about implementing it yourself.

Result

Name	Description	Type
activeId	returns the element id of the navigation that is active.

Parameters

The useScrollSpy hook accepts an object with the Intersection Observer API options.

Name	Description	Required
root	The element that is used as the viewport for checking visibility of the target.	No
rootMargin	Margin around the root. Can have values similar to the CSS margin property.	No
threshold	Either a single number or an array of numbers which indicate at what percentage of the target's visibility the observer's callback should be executed.	No