Managing CSS Custom Properties

css-in-js.ts

declare class CSSPropertyManager<T> {
    has<K extends keyof T>(property: K): asserts this is CSSPropertyManager<T & Required<T, K>;
    get<K extends keyof T>(property: K): boolean;
    set(property: keyof T, value: string): this;
}

const schema = {
  '--width-1': string;
}

const css = new CSSPropertyManager(schema, document);

css.get('--width-1');
css.set('--width-1', new CSSUnit({ unit: 'em', value: 22 }));