fullscreen js

function goFullScreen()
{
    // based on https://developers.google.com/web/fundamentals/native-hardware/fullscreen/
/*
    let documentElement = window.document.documentElement;
    let request = documentElement.requestFullscreen || documentElement.mozRequestFullScreen || documentElement.webkitRequestFullScreen || documentElement.msRequestFullscreen;
    request.call(documentElement);
*/
    let d = window.document.documentElement;
    (d.requestFullscreen || d.mozRequestFullScreen || d.webkitRequestFullScreen || d.msRequestFullscreen).call(d);
}

// must be called by an event handler in response to user interaction
// also, can be safely called multiple times (no need to check if already full screen), request will be simply ignored