Installation 🖥
npm install react-spring
Table of Contents 👇
- What is it?
- Why do we need yet another?
- Overview
- Render props, interpolation and native rendering
- Links
What is it? 🤔
A set of simple, spring-physics based primitives (as in building blocks) that should cover most of your UI related animation needs once plain CSS can't cope any longer. Forget easings, durations, timeouts and so on as you fluidly move data from one state to another. This isn't meant to solve each and every problem but rather to give you tools flexible enough to confidently cast ideas into moving interfaces.
Why do we need yet another? 🧐
react-spring is a cooked down fork of Christopher Chedeau's animated (which is used in react-native by default). It is trying to bridge it with Cheng Lou's react-motion. Although both are similarily spring-physics based they are still polar opposites.
Declarative | Primitives | Interpolations | Performance | |
---|---|---|---|---|
React-motion | ✅ | ✅ | ❌ | ❌ |
Animated | ❌ | ❌ | ✅ | ✅ |
React-spring | ✅ | ✅ | ✅ | ✅ |
react-spring builds upon animated's foundation, casting its imperative side out, making it leaner and more flexible. It inherits react-motions declarative api and goes to great lengths to simplify it. It has lots of useful primitives, can interpolate mostly everything and last but not least, can animate by committing directly to the dom instead of re-rendering a component frame-by-frame.
For a more detailed explanation read Why React needed yet another animation library.
Overview 🔭
Demo)
Springs (A Spring
will move data from one state to another. It remembers the current state, value changes are always fluid.
import Spring from 'react-spring' <Spring = => <div =>i will fade in</div></Spring>
Demo)
Mount/unmount Transitions (Transition
watches elements as they mount and unmount, it helps you to animate these changes.
import Transition from 'react-spring' <Transition = = = => items</Transition>
Demo)
2-state Reveals (Given a single child instead of a list you can reveal components with it.
import Transition from 'react-spring' <Transition = = => toggle ? ComponentA : ComponentB</Transition>
Demo)
Trails and staggered animations (Trail
animates the first child of a list of elements, the rest follow the spring of their previous sibling.
import Trail from 'react-spring' <Trail = = => items</Trail>
Demo)
Parallax and page transitions (Parallax
allows you to declaratively create page/scroll-based animations.
import Parallax ParallaxLayer from 'react-spring' <Parallax => <ParallaxLayer = => first Page </ParallaxLayer> <ParallaxLayer = => second Page </ParallaxLayer></Parallax>
Demo)
Time/duration-based implementations and addons (You'll find varying implementations under /dist/addons. For now there's a time-based animation as well common easings, and IOS'es harmonic oscillator spring. All primitives understand the impl
property which you can use to switch implementations.
import TimingAnimation Easing from 'react-spring/dist/addons' <Spring = = ...>
Demo)
Keyframes (Keyframes
orchestrates animations in a script that you provide. Theoretically you can even switch between primitives, for instance going from a Spring, to a Trail, to a Transition. It tries its best to remember the last state so that animations are additive. Animation can be awaited and return current props. Be warned: the keyframe API is still highly experiemental and can be subject to changes.
import Keyframes Spring from 'react-spring' <Keyframes => <div =>Hello</div></Keyframes>
Render props, interpolation and native rendering 🚀
Render props
The Api is driven by render props (though we do expose imperative Api as well). By principle we offer both render
and children
as well as prop forwardwing (unrecognized props will be spread over the receiving component).
const Header = children bold ...styles <h1 => bold ? <b>children</b> : children </h1> <Spring = = => hello there</Spring>
Interpolation
You can interpolate almost everything, from numbers, colors (names, rgb, rgba, hsl, hsla), paths (as long as the number of points match, otherwise use custom interpolation), percentages, units, arrays and string patterns:
<Spring =>
Native rendering
Libraries animate by having React recalculate the component-tree on every frame. Here it attempts to animate a component consisting of ~300 sub-components, plowing through the frame budget and causing jank. | React-spring with the native property renders the component only once, from then on the animation will be applied directly to the dom in a requestAnimationFrame-loop, similar to how gsap and d3 do it. |
import Spring animated from 'react-spring' <Spring = => <animated.div =>i will fade in</animated.div></Spring>
More about native rendering and interpolation here.
Links 🔗
Examples and Codesandboxes
Click for a combined example repository you can install as well as a collection of code-sandboxes to toy around with online.
API Overview
If you ever plan to use this library, this should be a must-read. It will go a little deeper into the primitives and how "native" rendering can make a large performance impact (for the better of course).
Full API reference
For annotated prop-types, good for finding out about all the obscure props that i don't want to bore you with (but which might come in handy, you never know).