README.md

ScrollSpy React Component

React Component, that automatically update navigation components based on scroll position to indicate which link is currently active in the viewport. It also scrolls (navigation) to viewport when click on a navigation component.

Demo with example code

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Table of Contents

• How to install
• How to use it
  • Step 1: Content
  • Step 2: Navigation
• Configuration
  • Optional ScrollSpy props
  • onClickEach(event, internalClickHandler, container)
  • onChangeActiveId(currentId, prevId)
• Compatibility
• Example code
• Guidelines
• License

How to install

Install via NPM or Yarn package manager

npm i react-scrollspy-navigation

yarn add react-scrollspy-navigation

How to use it

Step 1: Content

Add a unique id to content blocks or heading tags for the elements you want to spy on. There is nothing more to do with the content elements. It's awfully simple so far, right?

// Content blocks
conat ContentWithBoxes = () => {
  return (
    <>
      <section id="target-1">Content here</section>
      <section id="target-2">Content here</section>
      <section id="target-3">Content here</section>
    </>
)};

// Heading tags
conat ContentWithHeaders = () => {
  return (
    <>
      <section>
        <h2 id="target-1">Target 1</h2>
      </section>
      <section>
        <h2 id="target-2">Target 2</h2>
      </section>
      <section>
        <h2 id="target-3">Target 3</h2>
      </section>
    </>
)};

Step 2: Navigation

Wrap your navigation structure with ScrollSpy component. Use only a tags whose href attribute is the hash link of the id of an existing content element. You can use structures of any complexity or depth in the ScrollSpy component, and you can nest multiple ScrollSpy components (although this works, it is not recommended). Don't worry, ScrollSpy won't add any additional structures to the child component.

Note: If you are new to URL hashes, here is some information: https://en.wikipedia.org/wiki/URI_fragment

import ScrollSpy from 'react-scrollspy-navigation';

const Navigation = () => {
  return (
    <ScrollSpy activeClass="nav-active">
      <nav>
        <ul>
          <li>
            <a href="#target-1">...</a>
          </li>
          <li>
            <a href="#target-2">...</a>
          </li>
          <li>
            <a href="#target-3">...</a>
          </li>
        </ul>
      </nav>
    </ScrollSpy>
  );
};

Don't forget to specify in the activeClass prop what className to add to the currently active link. Congratulations, we are done, it was that simple. Continue reading the documentation to find out what options are available to configure how ScrollSpy works.

Note: The much loved Refs used in the previous version and React were thrown away.

Configuration

Optional ScrollSpy props

Prop	Type	Default	Description
activeClass	string	''	Class name(s) to be applied to the active link
activeAttr	boolean	false	If true, the active link will have an attribute data-active attached to it.
offsetTop	number	0	Offset the final scroll position from top in pixels.
offsetLeft	number	0	Offset the final scroll position from left in pixels.
behavior	'smooth' | 'instant' | 'auto'	'smooth'	Behavior of the scroll animation. See: Element: scrollTo()
root	HTMLElement | null	null	Root element for the intersection observer. See: IntersectionObserver: IntersectionObserver()
rootMargin	string	'0px'	Root margin for the intersection observer. See: IntersectionObserver: IntersectionObserver()
threshold	number | number[]	[0, 0.25, 0.5, 0.75, 1]	Thresholds for the intersection observer. See: IntersectionObserver: IntersectionObserver()
onClickEach	function	undefined	Callback function for handle the click event
onChangeActiveId	function	undefined	Callback function for handle the active element change event

onClickEach(event, internalClickHandler, container)

• event: The original click event
• internalClickHandler: The internal function that scrolls to the element. This should be called at the end of the onClickEach function, as you want the internal click handler to run.
• container: Container element that is being scrolled. Always try to find the scrollable parent of the linked element.

Example:

const Comp = () => {
  const onClickEach = (e, next, container) => {
    console.log('The clicked element:', e.target);
    console.log('The target container element:', container);
    next();
  };

  return <ScrollSpy onClickEach={onClickEach}>...</ScrollSpy>;
};

onChangeActiveId(currentId, prevId)

• currentId: The id of the active element
• prevId: The id of previous active element

Example:

const Comp = () => {
  const onChangeActiveId = (current, prev) => {
    console.log('Active element changed');
    console.log({ current, prev });
  };

  return <ScrollSpy onChangeActiveId={onChangeActiveId}>...</ScrollSpy>;
};

Compatibility

The component depends on the following functions or classes, which define its compatibility.

• Scroll methods on elements (scroll, scrollTo, scrollBy): supported browsers
• IntersectionObserver API: supported browsers
• Supported Environments: ESModules, CommonJS, TypeScript

Example code

Check out the interactive demo and example codes.

Demo with example code

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Guidelines

To learn about the guidelines, please read the Code of Conduct, Contributing and Security Policy documents.

License

MIT License @ 2021 Zsolt Tövis

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