Stylis

• ~2Kb minified+gzipped
• ~5kb minified

Stylis is a small css compiler that turns this

stylis('#user', styles);

Where styles is the following css

// variables
~~foo: 20px;

// flat css
font-size: 2em;
font-family: sans-serif;
width: var(~~foo);

// emulation for shadow dom selectors
:host {
    color: red;
}

:host(.fancy) {
    color: red;
}

:host-context(body) {
    color: red;
}

// removes line comment

.name {
    transform: rotate(30deg);
}

// inject to global scope block
@global {
    body {
        background: yellow;
    }
}

// inject to global scope inline
span, h1, :global(h2) {
    color:red;

    /**
     * removes block comments
     */
}

// prefixing
& {
    animation: slidein 3s ease infinite;
    display: flex;
    flex: 1;
    user-select: none;
}

// namespaced animations
&:before {
    animation: slidein 3s ease infinite;	
}

// namespaced keyframes
@keyframes slidein {
    from { transform: translate(10px); }
    to { transform: translate(200px); }
}

// flat namespaced css in @media
@media (max-width: 600px) {
    display: block;

    &, h1 { 
        appearance: none; 
    }
}

// nesting
h1 {
    color: red;

    h2 {
        display: block;

        h3, &:hover {
            color: blue;
        }
    }

    font-size: 12px;
}

// static mixins
@mixin large-text {
    font-size: 20px;
}

// function mixins
@mixin linx (link, visit, hover, active) {
    a {
        color: var(~~link);
        &:hover {
          color: var(~~hover);   
        }
    }
}

// use static mixins
& {
    @include large-text;
}

// use function mixins
@include linx(white, blue, green, red);

into this (minus the whitespace)

#user {
    font-size: 2em;
    font-family: sans-serif;
    width: 20px;
}
#user {
    color: red;
}
#user.fancy {
    color: red;
}
body #user {
    color: red;
}
#user .name {
    -webkit-transform: rotate(30deg);
    -ms-transform: rotate(30deg);
    transform: rotate(30deg);
}
body {
    background: yellow;
}
#user span,
#user h1,
h2 {
    color: red;
}
#user {
    display: -webkit-flex;
    display: flex;

    -webkit-flex: 1;
    -moz-flex: 1;
    flex: 1;

    -webkit-user-select: none;
    -moz-user-select: none;
    -ms-user-select: none;
    user-select: none;

    -webkit-animation: userslidein 3s ease infinite;
    animation: userslidein 3s ease infinite;
}
#user:before {
    -webkit-animation: userslidein 3s ease infinite;
    animation: userslidein 3s ease infinite;
}
@-webkit-keyframes userslidein {
    from {
        -webkit-transform: translate(10px);
        -ms-transform: translate(10px);
        transform: translate(10px);
    }
    to {
        -webkit-transform: translate(200px);
        -ms-transform: translate(200px);
        transform: translate(200px);
    }
}
@keyframes userslidein {
    from {
        -webkit-transform: translate(10px);
        -ms-transform: translate(10px);
        transform: translate(10px);
    }
    to {
        -webkit-transform: translate(200px);
        -ms-transform: translate(200px);
        transform: translate(200px);
    }
}
@media (max-width: 600px) {
    #user, #user h1 {
        -webkit-appearance: none;
        -moz-appearance: none;
        appearance: none;
    }

    #user {
        display: block;
    }
}

#user h1 {
    color: red;
    font-size: 12px;
}

#user h1 h2 {
    display: block;
}

#user h1 h2 h3,
#user h1 h2 h2:hover {
    color: blue;
}

#user {
    font-size: 20px;
}

#user a {
    color: white;
    &:hover {
      color: green;   
    }
}

Supports

• Edge
• IE 9+
• Chrome
• Firefox
• Safari
• Node.js

Installation

direct download

<script src=stylis.min.js></script>

CDN

<script src=https://unpkg.com/stylis@0.10.0/stylis.min.js></script>

npm

npm install stylis --save

Features

• variables via ~~foo and var(~~foo);
• web component emulation of :host, :host() and :host-context()
• inline global injection via :global(selector)
• block level global injection via @global {}
• nesting a { &:hover {} }
• static and function mixins via @mixin ... and @include
• prefixer
• namespacing
• flat css color: red; h1 { color: red; }
• middleware support
• keyframes and animation namespacing (with the option to disable)

API

stylis(
    selector: {string},     // selector - i.e `.class` or `#id` or `[attr=id]`
    styles: {string},       // css string
    animations: {boolean=}  // false to prevent prefixing animations, true by default
    compact: {boolean=}     // enable additional features (mixins, variables)
    middleware: {function=}
);

Middleware

The optional middleware function accepts four arguments ctx, str, line, column, the middleware is executed at 4 stages.

1. at every selector declaration ctx = 0 i.e .class / .foo, .bar
2. at every property declaration ctx = 1 i.e color: red;
3. before a block of compiled css is added to the output string ctx = 2, i.e .class {color:red;}
4. when flat css is appened to the output bundle ctx = 3, i.e .prefix { color:red; }
5. When an import statement is found ctx = 4, i.e import 'foo'

If you wanted to you could parse import statements in the middleware and return the imported file, stylis will then insert the content of it into the css that it later parse/compile. The str value on import context is the file name i.e foo or foo.scss or multiple files foo, bar.

For any stage if the middleware returns a non-falsey value the token or block of css will be replaced with the return value. For example we can add a feature random() that when used prints a random number.

stylis(``, `h1 { width: calc(random()*10); }`, false, function (ctx, str, line, column) {
    switch (ctx) {
        // str will be `width: calc(random()*10);`
        case 1: return str.replace(/random\(\)/g, Math.random());
    }
});

Will replace all instances of random() with a random number

Intergration

You can use stylis to build an abstraction ontop of, for example imagine we want to build an abstract that makes the following React Component possible

class Heading extends React.Component {
    stylesheet(){
        return `
            &{
                color: blue
            }
        `;
    }
    render() {
        return (
            React.createElement('h1', 'Hello World')
        );
    }
}

We could simply extend the Component class as follows

React.Component.prototype.stylis = function (self) {
    var namespace = this.displayName;

    return function () {
        stylis(namespace, self.stylesheet(), document.head);
        mounted = true;
        this.setAttribute(namespace);
    }
}

Then use it in the following way

class Heading extends React.Component {
    stylesheet(){
        return `
            &{
                color: blue
            }
        `;
    }
    render() {
        return (
            React.createElement('h1', {ref: this.stylis(self)}, 'Hello World')
        );
    }
}

When the first instance of the component is mounted the function assigned to the ref will get executed adding a style element with the compiled output of stylesheet() where as only the namespace attribute is added to any subsequent instances.

You can of course do this another way

class Heading extends React.Component {
    constructor (props) {
        super(props);
        // or you can even inline this
        this.style = React.createElement('style', {id: this.displayName}, this.stylesheet());
    }
    stylesheet(){
        return `
            &{
                color: blue
            }
        `;
    }
    render() {
        return (
            React.createElement('h1', null, 'Hello World', this.style)
        );
    }
}

One will add it to the head another will render it in place with the component.

If you want a better picture into what can be done, there is an abstraction i created for dio.js that does away with the above boilerplate entirely http://jsbin.com/mozefe/1/edit?js,output