Function extractCssCustomProperties

packages/css-data/src/parse-css.ts:680–702

(
  css: string
)

 * to be resolved together as if they apply to the same element.
 */
export const extractCssCustomProperties = (
  css: string
): Map<string, string> => {
  const map = new Map<string, string>();
  const ast = cssTreeTryParse(css);
  if (ast === undefined) {
    return map;
  }
  csstree.walk(ast, {
    visit: "Declaration",
    enter(node) {
      const decl = node as csstree.Declaration;
      const prop = normalizeProperty(decl.property);
      if (prop.startsWith("--")) {
        const value = getRawDeclarationValue(css, decl);
        if (value !== undefined && isValidCustomPropertyValue(value)) {
          map.set(prop, normalizeCustomPropertyValue(value));
        }
      }
    },
  });
  return map;
};

export const parseCss = (
  css: string,