import { Logger } from '@empathyco/x-logger';
import { StorageService } from './storage-service';
/**
 * In browser implementation of the storage service.
 *
 * @public
 */
export declare class BrowserStorageService implements StorageService {
    private storage;
    private prefix;
    protected logger: Logger;
    constructor(storage?: Storage, prefix?: string);
    /**
     * Adds a new item in the browser storage.
     *
     * @param key - The key of the item.
     * @param item - The item to save.
     * @param ttlInMs - The TTL in ms of the item in the browser storage.
     *
     * @public
     */
    setItem(key: string, item: any, ttlInMs?: number): void;
    /**
     * Retrieves an item by its key.
     *
     * @param key - The key of the item.
     * @returns The founded item or null.
     *
     * @public
     */
    getItem<Item = any>(key: string): Item | null;
    /**
     * Removes an item by its key.
     *
     * @param key - The key of the item.
     * @returns The removed item or null.
     *
     * @public
     */
    removeItem<Item = any>(key: string): Item | null;
    /**
     * Clears the storage..
     *
     * @returns The number of removed items.
     *
     * @public
     */
    clear(): number;
    protected prefixKey(key: string): string;
    protected createExpirableItem(item: any, ttlInMs?: number): any;
    protected currentTimestamp(): number;
    protected getItemValue(item: any): any;
    protected getOwnKeys(): string[];
    protected removeExpiredItems(): void;
}