w3cCSS definitions of the web platform
This package contains a consolidated list of CSS features defined across specs, scraped from the latest versions of web platform specifications in webref. Fixes are applied to ensure that guarantees hold, including the ability to parse syntaxes associated with CSS features with CSSTree.
Important: If you're migrating from version 6, see the changelog for "How to upgrade" considerations.
API
The async listAll() method resolves with an object that contains lists of features grouped by feature type: atrules, functions, properties, selectors and types. Example:
const css = require('@webref/css');
const { atrules, functions, properties, selectors, types } = await css.listAll();
for (const feature of functions) {
// do something with the object that describes the CSS function
}
Each CSS feature is described by:
- a
namekey that contains the name of the feature - an
hrefkey that contains the URL (with a fragment) of the CSS spec that defines the feature
Many CSS features also have a value key that describes the syntax of the feature, as defined in the spec. This syntax can be parsed with the CSSTree Value Definition Syntax parser. Example:
const css = require('@webref/css');
const { definitionSyntax } = require('css-tree');
const { properties } = await css.listAll();
for (const property of properties) {
if (!property.value) {
continue;
}
const ast = definitionSyntax.parse(property.value);
// do something with the abstract syntax tree
}
Additional keys may be set depending on the type of the CSS feature. For example:
- At-rules have a
descriptorskey that contains the list of descriptors defined for the given at-rule. - Functions and types that are scoped to a property or other feature have a
forkey that contains the name of the scoping property or other feature. - Properties have a
styleDeclarationkey that contains the list of IDL attribute names that the property generates. A number of other keys may be set to describe the property's initial value, animation type and other parameters.
Additional notes:
- Type names are enclosed in
<>. For example:<frequency-percentage>. - When a feature is defined across different levels in the same spec series, the definition from the latest level is used.
- When a property is extended with new values in different specs,
hreflinks to the base definition andvalueis the union (using|) of the syntaxes of the base and extended definitions. - When new descriptors are defined for an at-rule in different specs,
descriptorscontains the merged list of known descriptors. - When specs define the syntax of an at-rule in terms of
<declaration-list>or<declaration-rule-list>, thevaluekey contains an "expanded" syntax that leverages the syntax of the at-rule's descriptors.
Guarantees
The following guarantees are provided by this package:
- All syntax values (the
valuekeys) can be parsed by the version of CSSTree set inpeerDependenciesinpackage.json. - Feature names (the
namekeys) are unique per type provided that theforkey is also taken into account for functions and types. - All features have an
hrefkey that targets the CSS spec that defines the feature. When the feature is extended across CSS specs, this URL targets the base definition.
Note: there is no guarantee that functions, properties and types referenced by other constructs actually exist. The grammar is known to be incomplete.