6.12.1 • Public • Published

CSS definitions of the web platform

This package contains CSS property definitions scraped from the latest versions of web platform specifications in webref, with fixes applied to ensure (almost) all CSS value definitions can be parsed with CSSTree.


The async listAll() method resolves with an object where the keys are spec shortnames, and the values are the data for that spec. Example:

const css = require('@webref/css');

const parsedFiles = await css.listAll();
for (const [shortname, data] of Object.entries(parsedFiles)) {
  // do something with the json object

CSS fragments that appear in the objects, in other words the contents of the properties[].value, properties[].newValues, atrules[].value, atrules[].descriptors[].value, selectors[].value and values[].value properties can be parsed with the CSSTree Value Definition Syntax parser. Example:

const css = require('@webref/css');
const { definitionSyntax } = require('css-tree');

const parsedFiles = await css.listAll();
for (const [shortname, data] of Object.entries(parsedFiles)) {
  for (const property of data.properties) {
    if (property.value) {
      try {
        const ast = definitionSyntax.parse(property.value);
        // do something with the ast
      catch {
        // one of the few value definitions that cannot yet be parsed by CSSTree


The following guarantees are provided by this package:

  • All values in CSS files can be parsed by the version of CSSTree used in peerDependencies in package.json.
  • No duplicate definitions of CSS properties provided that CSS extracts of delta specs are not taken into account (such extracts end with -n.json, where n is a level number).
  • CSS extracts contain a base definition of all CSS properties that get extended by other CSS property definitions (those for which newValues is set).
  • All entries in CSS files that do not extend a base definition link back to their actual definition in the spec. In other words, all entries under properties[], properties[].values[], selectors[], atrules[] and values[] have an href key that contains an absolute URL with fragment, except properties that that have a newValues key, at-rules that neither have a prose nor a value key, and definitions of a delta spec that completely override a definition in a previous level.




Package Sidebar


npm i @webref/css

Weekly Downloads






Unpacked Size

1.69 MB

Total Files


Last publish


  • tidoust
  • dontcallmedom
  • foolip