JavaScript implementation of CSS.

const { cssom, install, parser: { parseCSSGrammar, parseCSSStyleSheet } } = require('@cdoublev/css')

/**
 * install() expects a window-like global object (default: globalThis) with
 * document, Array, Object, Number, String, TypeError.
 */
install(/*myGlobalObject*/)

// Parse a style sheet and get a (non-constructed) CSSStyleSheet
const stylesheet = parseCSSStyleSheet('style {}')

// Create a (constructed) CSSStyleSheet
const styleSheet = new /*myGlobalObject.*/CSSStyleSheet()

// Create a CSSStyleSheet or CSSStyleDeclaration wrapper
const stylesheet = cssom.CSSStyleSheet.create(myGlobalObject, undefined, privateProperties)
const style = cssom.CSSStyleDeclaration.create(myGlobalObject, undefined, privateProperties)

// Parse a value according to a CSS grammar
const value = parseCSSGrammar('(width < 30rem), (orientation: portrait)', '<media-query-list>')

The webidl2js wrappers are intended to implement:

• create a CSS style sheet: when processing or updating the content of HTMLStyleElement, when processing the resource referenced by HTMLLinkElement or an HTTP Link header with rel="stylesheet"
• (get) the style attribute of an HTMLElement
• return a live CSS declaration block from Window.getComputedStyle()

To sum up, they mostly exist to create CSSStyleSheet and CSSStyleDeclaration. Below are the properties defined in the CSSOM specification and their associated property read in privateProperties:

CSSStyleSheet

• CSS rules: rules (String or ReadableStream)
• alternate flag: alternate (Boolean, optional, default: false)
• disabled flag: disabled (Boolean, optional, default: false)
• location: location (String, optional, default: null)
• media: media (String or MediaList)
• origin-clean flag: originClean (Boolean)
• owner CSS rule: ownerRule (CSSRule, optional, default: null)
• owner node: ownerNode (HTMLElement)
• parent CSS style sheet: parentStyleSheet (CSSStyleSheet, optional, default: null)
• title: title (String, optional, default: '')

CSSStyleDeclaration

• computed flag: computed (Boolean, optional, default: false)
• declarations: declarations ([Declaration], optional, default: [])
• owner node: ownerNode (HTMLElement, optional, default: null)
• parent CSS rule: parentRule (CSSRule, optional, default: null)

Declaration must be a plain object with the following properties:

• name: String
• value: String
• important: Boolean (optional, default: false)