/**
 * Custom hook to manage state synchronized with localStorage.
 * Value must by serializable to JSON.
 *
 * @template T - The type of the state value.
 * @param {string} key - The key under which the state is stored in localStorage.
 * @param {T} defaultValue - The default value to use if no value is found in localStorage.
 * @returns Returns a tuple containing the current state and a function to update the state.
 *
 * @example
 * const [value, setValue] = useLocalStorageState<string>('myKey', 'default');
 * setValue((oldValue) => 'newValue');
 */
export declare function useLocalStorageState<T>(key: string, defaultValue: T): readonly [T, (updater: (old: T) => T) => void];
export declare namespace useLocalStorageState {
    var update: (key: string, value: any) => void;
}