JarCastingSTYLIS
A Light–weight CSS Preprocessor.
Installation
- Use a Direct Download:
<script src=stylis.js></script> - Use a CDN:
<script src=unpkg.com/stylis></script> - Use NPM:
npm install stylis --save
Features
- nesting
a { &:hover {} } - selector namespacing
- vendor prefixing (flex-box, etc...)
- minification
- esm module compatible
- tree-shaking-able
Abstract Syntax Structure
const declaration = {
value: 'color:red;',
type: 'decl',
props: 'color',
children: 'red',
line: 1, column: 1
}
const comment = {
value: '/*@noflip*/',
type: 'comm',
props: '/',
children: '@noflip',
line: 1, column: 1
}
const ruleset = {
value: 'h1,h2',
type: 'rule',
props: ['h1', 'h2'],
children: [/* ... */],
line: 1, column: 1
}
const atruleset = {
value: '@media (max-width:100), (min-width:100)',
type: '@media',
props: ['(max-width:100)', '(min-width:100)'],
children: [/* ... */],
line: 1, column: 1
}
Example:
import {compile, serialize, stringify} from 'stylis'
serialize(compile(`h1{all:unset}`), stringify)
Compile
compile('h1{all:unset}') === [{value: 'h1', type: 'rule', props: ['h1'], children: [/* ... */]}]
compile('--foo:unset;') === [{value: '--foo:unset;', type: 'decl', props: '--foo', children: 'unset'}]
Tokenize
tokenize('h1 h2 h3 [h4 h5] fn(args) "a b c"') === ['h1', 'h2', 'h3', '[h4 h5]', 'fn', '(args)', '"a b c"']
Serialize
serialize(compile('h1{all:unset}'), stringify)
Middleware
The middleware helper is a convenient helper utility, that for all intents and purposes you can do without if you intend to implement your own traversal logic. The stringify middleware is one such middleware that can be used in conjunction with it.
Elements passed to middlewares have a root property that is the immediate root/parent of the current element in the compiled output, so it references the parent in the already expanded CSS-like structure. Elements have also parent property that is the immediate parent of the current element from the input structure (structure representing the input string).
Traversal
serialize(compile('h1{all:unset}'), middleware([(element, index, children) => {
assert(children === element.root.children && children[index] === element.children)
}, stringify])) === 'h1{all:unset;}'
The abstract syntax tree also includes an additional return property for more niche uses.
Prefixing
serialize(compile('h1{all:unset}'), middleware([(element, index, children, callback) => {
if (element.type === 'decl' && element.props === 'all' && element.children === 'unset')
element.return = 'color:red;' + element.value
}, stringify])) === 'h1{color:red;all:unset;}'
serialize(compile('h1{all:unset}'), middleware([(element, index, children, callback) => {
if (element.type === 'rule' && element.props.indexOf('h1') > -1)
return serialize([{...element, props: ['h2', 'h3']}], callback)
}, stringify])) === 'h2,h3{all:unset;}h1{all:unset;}'
Reading
serialize(compile('h1{all:unset}'), middleware([stringify, (element, index, children) => {
assert(element.return === 'h1{all:unset;}')
}])) === 'h1{all:unset;color:red;}'
The middlewares in src/Middleware.js dive into tangible examples of how you might implement a middleware, alternatively you could also create your own middleware system as compile returns all the nessessary structure to fork from.
Benchmark
Stylis is at-least 2X faster than its predecesor.
License
Stylis is MIT licensed.