react-scroll-parallax

React Scroll Parallax

Provides a React component and single global passive scroll listener to add vertical scrolling based offsets to elements based on their position in the viewport. Works with universal (server-side rendered) React apps.

View on NPM

Examples

🔗 CodePen Parallax

🔗 Example Site

🔗 Parallax Testing

Install

npm i react-scroll-parallax --save

Usage

Import ParallaxController on the client side and call ParallaxController.init() to create the global ParallaxController on the window which will handle controlling all parallax elements on scroll. Ideally, this would be called at the root of your react app on the client.

import { ParallaxController } from 'react-scroll-parallax';

ParallaxController.init();

Import the Parallax component...

import { Parallax } from 'react-scroll-parallax';

... then use it like so:

<Parallax
    className="custom-class"
    offsetYMax={20}
    offsetYMin={-20}
    slowerScrollRate
    tag="figure"
>
    <img src="/image" />
</Parallax>

NOTE: ParallaxController caches the scroll state and positions of elements on the page for performance reasons. This means that if the page height changes (perhaps from images loading) after <Parallax /> components are mounted it won't properly determine when the elements are in view. To correct this call the update() from the global ParallaxController once every thing has loaded and is ready.

Parallax Component Props

The following are all props that can be passed to the React <Parallax /> component:

className

• type: String

Optionally pass additional class names to be added to the outer parallax element.

disabled

• type: Boolean
• default: false

Determines if the component will have parallax offsets applied. If true parallax styles are completely removed from the element and it is no longer updated.

offsetXMax

• type: Number or String
• default: 0

Maximum x offset in % or px. If no unit is passed percent is assumed. Percent is based on the elements width.

offsetXMin

• type: Number or String
• default: 0

Minimum x offset in % or px. If no unit is passed percent is assumed. Percent is based on the elements width.

offsetYMax

• type: Number or String
• default: 0

Maximum y offset in % or px. If no unit is passed percent is assumed. Percent is based on the elements height.

offsetYMin

• type: Number or String
• default: 0

Minimum y offset in % or px. If no unit is passed percent is assumed. Percent is based on the elements height.

slowerScrollRate

• type: Boolean
• default false

Determines whether the scroll rate of the parallax component will move faster or slower than the default rate of scroll.

tag

• type: String
• default div

Optionally pass a tag name to be applied to the outer most parallax element. For example: <Parallax tag="figure" />.

Parallax Controller

init()

Initilize the ParallaxController on the client with the init static method.

NOTE: Calling ParallaxController.init() creates an instance of the controller on the window using the same name, e.g. window.ParallaxController.

The following are public methods available on the window.ParallaxController global:

update()

Updates all cached attributes for parallax elements then updates their positions.

destroy()

Removes window scroll and resize listeners, resets all styles applied to parallax elements, and sets the global ParallaxController to null.

Support

React scroll parallax should support the last two versions of all major browsers and has been tested on desktop Chrome, Firefox, Safari and Edge, as well as the following: iOS 9, iOS 10, Android 4 and IE11. If you encounter any errors for browsers that should be supported please post an issue.

Development

Install node modules and start webpack:

npm i

Run webpack watch:

npm run dev

Run dev server:

npm run dev-server

Run Jest tests:

npm run test

Optimizations to Reduce Jank

React Scroll Parallax uses a single passive scroll listener (dependent on browser support) with the minimal amount of work done on the scroll event to prevent jank (calculations that cause layout, reflow and paint are cached initially and only updated when layout changes). Request animation frame is then used to decouple the scroll handler and further reduce jank. All offsets are applied with 3D transforms to utilize the GPU and prevent paints. If you have ideas to further optimize scrolling please PR or post an issue.

PSA

It's 2017 and you probably shouldn't be building parallax sites—but if you do (like I did) and you use this package try and use it responsibly. Keeping images small and optimized, reducing the number of moving elements in view and on the page, and disabling scroll effects on mobile devices should help achieve silky smooth animations.