export declare function isValidHttpUrl(s: string): boolean;
export declare function hasValidFamilyQueryParam(url: string): boolean;
export declare function transform(fontUrl: string, familyKey?: string): string;
/**
 * createLinkElement
 * @param fontUrlStruct {UniqueFontObject | String}
 * @returns element {HtmlLinkElement}
 */
export declare const createLinkElement: (fontUrlStruct: string, fontKey?: string) => HTMLLinkElement;
/**
 * Removes an HtmlElement from the DOM, used in useEffect cleanup
 * @param element {HtmlElement}
 */
export declare const destroyLinkElement: (element: HTMLElement) => void;
/**
 * Checks the DOM for an existing link el with the corresponding href
 * @param key String
 * @returns Boolean
 */
export declare const checkDOMTreeForLinkEl: (url: string, familyKey?: string) => boolean;