export function getFullscreenElement() {
    return document.fullscreenElement
        || document.webkitFullscreenElement
        || document.mozFullscreenElement
        || document.msFullscreenElement;
}
 
export function doFullscreen() {
    if (getFullscreenElement()) {
        document.exitFullscreen();
    } else {
        document.documentElement.requestFullscreen().catch(err => console.error);
    }
}