export declare let preferredStorage: WebStorage | null;
export interface WebStorage {
    getItem(key: string): string | null | Promise<string | null>;
    removeItem(key: string): void;
    setItem(key: string, data: string): void | Promise<void>;
}
export declare function getAvailableStorage(): WebStorage;
export declare class CookieStorage implements WebStorage {
    static prefix: string;
    getItem(key: string): string | null;
    removeItem(key: string): void;
    setItem(key: string, data: string, expire?: number): void;
}
export declare class CookieAndLocalStorage implements WebStorage {
    private cookieStorage;
    getItem(key: string): string | null;
    removeItem(key: string): void;
    setItem(key: string, data: string): void;
}
export declare class NullStorage implements WebStorage {
    getItem(key: string): string | null;
    removeItem(key: string): void;
    setItem(key: string, data: string): void;
}