@fullhuman/postcss-purgecss

const purgeCSSPlugin: postcss.PluginCreator<UserDefinedOptions>;

type ComplexSafelist = {
    standard?: StringRegExpArray;
    /**
     * You can safelist selectors and their children based on a regular
     * expression with `safelist.deep`
     *
     * @example
     *
     * ```ts
     * const purgecss = await new PurgeCSS().purge({
     *   content: [],
     *   css: [],
     *   safelist: {
     *     deep: [/red$/]
     *   }
     * })
     * ```
     *
     * In this example, selectors such as `.bg-red .child-of-bg` will be left
     * in the final CSS, even if `child-of-bg` is not found.
     *
     */
    deep?: RegExp[];
    greedy?: RegExp[];
    variables?: StringRegExpArray;
    keyframes?: StringRegExpArray;
};

type ExtractorFunction<T = string> = (content: T) => ExtractorResult;

type ExtractorResult = ExtractorResultDetailed | string[];

type StringRegExpArray = Array<RegExp | string>;

type UserDefinedSafelist = StringRegExpArray | ComplexSafelist;