reveal-js-logitech-r400-fullscreen.js

			var funStartStopMedia = function() {
				console.log("play/stop");
				var sl = Reveal.getCurrentSlide();
				var e  = sl.getElementsByTagName("audio")[0];
				if (typeof e == 'undefined') {
					e = sl.getElementsByTagName("video")[0];
				};
				if (typeof e !== 'undefined') {
					if (e.paused) {
						e.play();
						e.requestFullscreen();   // doesn't work
					} else {
						e.pause();
						document.exitFullscreen();
					}
				};
			};

			Reveal.configure({
				keyboard: {
					 27: funStartStopMedia, // logitech r400: escape
					116: funStartStopMedia, // logitech r400: f5
					// 190: () => { alert("stop") },
				},
				transition: 'fade'
			});

/*

 for this to work, use `about:config` and set
 `full-screen-api.allow-trusted-requests-only` to `false`

*/