export declare class KeyboardService {
    private _isListening;
    private _isKeyPressed;
    private _history;
    private _shiftPressed;
    private _metaPressed;
    private _callbacks;
    constructor();
    listen(toListen?: boolean): void;
    isBrowserRefreshKey(keyCode: number): boolean;
    onKeyCode(keyCode: number, callback: Function): void;
    getIndex(keyCode: number): number;
    getHistory(): number[];
    getHistoryKeys(): string[];
    getLastKeyCode(): number;
    getLastKey(): string;
    getShiftPressed(): boolean;
}