postcss-spring-easing

NPM | GitHub | Licence

Want your CSS animations to bounce and boogie 🕺 ? You've come to the right place!

This PostCSS plugin gives your CSS the superpower to create "spring" animations, bringing your websites to life! Inspired by postcss-easings, it replaces spring() functions with a linear() easing function.

Here's a glimpse of how you can use it in your CSS:

.snake {
  transition: all var(--spring-duration) spring-out;
}
.camel {
  transition: all var(--spring-duration) springOut;
}

And here's what it looks like once postcss-spring-easing works its magic:

.snake {
  --spring-duration: 1333.33ms; 
  transition: all var(--spring-duration) linear(0, -0.003 24.3%, 0.025 43.2%, 0.024, 0.004 54.1%, -0.016 56.8%, -0.132 67.6%, -0.155, -0.163, -0.149, -0.107, -0.029, 0.086, 0.239 86.5%, 0.801 94.6%, 0.943, 1); 
} 
.camel {
  --spring-duration: 1333.33ms; 
  transition: all var(--spring-duration) linear(0, -0.003 24.3%, 0.025 43.2%, 0.024, 0.004 54.1%, -0.016 56.8%, -0.132 67.6%, -0.155, -0.163, -0.149, -0.107, -0.029, 0.086, 0.239 86.5%, 0.801 94.6%, 0.943, 1); 
}

Note: all the easings spring-easing supports postcss-spring-easing supports as well.

Why use postcss-spring-easing? 🤔

CSS is great for designing your websites, including adding animations. But there are certain animation types, like a "spring" animation (imagine a bouncy ball), which CSS alone can't pull off.

Fun fact: "spring" animations are how Apple is able to create smooth animations for the iPhone.

Check out more examples on Codepen.

postcss-spring-easing comes to your rescue! It's a plugin for PostCSS, which enhances the capabilities of your CSS. This plugin helps you craft spring animations effortlessly.

In a nutshell, postcss-spring-easing is a simple and effective tool for creating bouncy animations with minimum fuss, making your web pages more dynamic and fun.

Let's get coding! 🚀

Installation

npm install postcss-spring-easing

Others

yarn add postcss-spring-easing

or

pnpm install postcss-spring-easing

Setting up PostCSS

To use this plugin, you need to have PostCSS set up in your project. If you haven't already, follow these steps:

First, install PostCSS:

npm install postcss

Others

yarn add postcss

or

pnpm install postcss

Check your project for an existing PostCSS config: postcss.config.js in the project root,"postcss" section in the package.json or postcss in your bundle config.

Add the plugin to plugins list:

module.exports = {
  plugins: [
+   require('postcss-spring-easing').default,
    require('autoprefixer')
  ]
}

Or

// dependencies
var fs = require("fs")
var postcss = require("postcss")
var { springEasingPlugin } = require("postcss-spring-easing")

// css to be processed
var css = fs.readFileSync("input.css", "utf8")

// process css
var output = postcss()
  .use(springEasingPlugin())
  .process(css)
  .css

Checkout tests for more examples.

Usage

To create a spring animation, you just need to write your CSS transitions as usual, but replace the timing function with one of the following:

• spring
• spring-in
• spring-out
• spring-in-out
• spring-out-in

Each of these represents a different type of spring effect.

For example:

.box {
  transition: transform 1s spring-out;
}

This will give a spring effect to the transform transition of the .box element.

The spring-out function here means that the animation will start slowly and end quickly, like a spring being released. Similarly, spring-in would start quickly and end slowly, and spring-in-out would start and end slowly with a quick middle, resembling the movement of a bouncing spring.

Now your animations are ready to bounce!

Have questions? Or just wanna talk--leave a message on GitHub Discussions

Showcase

A couple sites/projects that use postcss-spring-easing:

• Your site/project here...

Options

postcss-spring-easing has 4 options they are

• easing (all the easings from EasingFunctions are supported),
• easings (list of extra custom easings to support),
• decimal (the number of decimal places of the resulting values), and
• quality (how detailed/smooth the spring easing should be)

Properties	Default Value
easing	spring(1, 100, 10, 0)
easings	{}
decimal	3
quality	0.85

easing

By default, spring easings are supported in the form,

constant	accelerate	decelerate	accelerate-decelerate	decelerate-accelerate
	spring / spring-in	spring-out	spring-in-out	spring-out-in

All Spring easing's can be configured using theses parameters,

spring-*(mass, stiffness, damping, velocity)

Each parameter comes with these defaults

Parameter	Default Value
mass	1
stiffness	100
damping	10
velocity	0

To understand what each of the parameters of SpringEasing mean and how they work I suggest looking through the SpringEasing API Documentation

For a full understanding of what is happening in the SpringEasing library, pleace check out its API site for detailed API documentation.

a {
  transition: all var(--spring-duration) spring(1, 100, 10, 0);
}

easings

Allow to set custom easings:

require('postcss-spring-easing').default({
  easings: { 
    bounceOut: t => {
      let pow2, b = 4;
      while (t < ((pow2 = Math.pow(2, --b)) - 1) / 11) { }
      return 1 / Math.pow(4, 3 - b) - 7.5625 * Math.pow((pow2 * 3 - 2) / 22 - t, 2);
    },
  }
})

The plugin will convert custom easing name between camelCase and snake-case. So the example above would work for bounce-out and bounceOut easings.

Browser Support

Chrome	Edge	Firefox	Safari	IE
113+	113+	112+	-	-

postcss-spring-easing is meant for browsers which have support for the linear() easing function, which as of right now is Chrome & Edge 113 + Firefox 112, Safari doesn't support it yet.

Contributing

I encourage you to use pnpm to contribute to this repo, but you can also use yarn or npm if you prefer.

Install all necessary packages

npm install

Then run tests

npm test

Build project

npm run build

Note: this project uses Conventional Commits standard for commits, so, please format your commits using the rules it sets out.

Licence

See the LICENSE file for license rights and limitations (MIT).

The CSSSpringEasing, getOptimizedPoints and getLinearSyntax functions from spring-easing which are used in postcss-spring-easing are based of the work done by Jake Archibald in his Linear Easing Generator and are thus licensed under the Apache License 2.0.