Duck-typing fix. Less `typeof`, more casting.

scripts/script.js

-var url = document.location,
+(function () {
+	var url = document.location,
 		linkScreen = document.querySelector('link[title=screen]'),
 		linkProjection = document.querySelector('link[title=projection]'),
 		shower = document.querySelector('div.shower'),
@@ -6,26 +7,28 @@ var url = document.location,
 		slideList = [], hashList = {},
 		fullscreen = false;
 
-for(var i = 0, slidesLength = slides.length; i < slidesLength; i++) {
+	for(var i = 0, slidesLength = slides.length; i < slidesLength; i++) {
 		var id = slides[i].id;
 		slideList[i] = '#' + id;
 		hashList['#' + id] = i;
-}
+	}
 
-function toggleFull(force) {
-	fullscreen = (typeof force == 'boolean') ? force : (
+	function toggleFull(force) {
+		fullscreen = (force != null) ? !!force : (
 			window.fullScreen || // Firefox
 			document.webkitFullScreen || // Webkit
 			screen.width == window.outerWidth && screen.height == window.outerHeight
 		);
 		updateView();
-}
+	}
 
-function turnSlide(e) {
+	function turnSlide(e) {
 		if(!fullscreen) return;
 		var current = hashList[url.hash],
 			target;
-	if(e.type == 'keyup') { // Key-Based
+		if(e == null) {
+			target = slideList[current++];
+		} else if(e.type == 'keyup') { // Key-Based
 			switch(e.which) {
 				case 33 : // PgUp
 				case 38 : // Up
@@ -45,30 +48,27 @@ function turnSlide(e) {
 			}
 			target = slideList[current];
 			e.preventDefault();
-	}
-	if(typeof e == 'number') { // Specific
-		target = slideList[e];
-	}
-	if(typeof e == 'undefined') { // Next
-		target = slideList[current++];
+		} else { // Specific
+			target = slideList[+e || 0];
 		}
 		if(target) url.hash = target;
-}
+	}
 
-function updateView() {
+	function updateView() {
 		linkScreen.disabled = fullscreen;
 		linkProjection.disabled = !fullscreen;
 		if(!hashList[url.hash]) turnSlide(0);
-}
+	}
 
-slides[0].addEventListener('click', function(){
+	slides[0].addEventListener('click', function(){
 		toggleFull(true);
-}, false);
+	}, false);
 
-document.addEventListener('keyup', turnSlide, false);
-document.addEventListener('keyup', function(e) {
+	document.addEventListener('keyup', turnSlide, false);
+	document.addEventListener('keyup', function(e) {
 		if(e.which == 27) toggleFull(false);
-}, false);
+	}, false);
 
-window.addEventListener('resize', toggleFull, false);
-window.addEventListener('DOMContentLoaded', toggleFull, false);
\ No newline at end of file
+	window.addEventListener('resize', toggleFull, false);
+	window.addEventListener('DOMContentLoaded', toggleFull, false);
+})();
\ No newline at end of file