Testing addition of pseudo page visibility API

assets/scripts/utils/visibility.js

@@ -0,0 +1,36 @@
+/* jshint esnext: true */
+import { $document, $window, $html, $body } from '../utils/environment';
+
+const CALLBACKS = {
+	hidden: [],
+	visible: []
+};
+
+// Main event
+$document.on('visibilitychange', function(event) {
+	if(document.hidden){
+		onDocumentChange('hidden');
+	}else{
+		onDocumentChange('visible');
+	}
+});
+
+function registerDocumentHiddenCallback(callback) {
+	CALLBACKS['hidden'].push(callback);
+}
+
+function registerDocumentVisibleCallback(callback) {
+	CALLBACKS['visible'].push(callback);
+}
+
+function onDocumentChange(state) {
+	let callbacks = CALLBACKS[state];
+	let i = 0;
+	let len = callbacks.length;
+
+	for (; i < len; i++) {
+		callbacks[i]();
+	}
+}
+
+export {registerDocumentHiddenCallback, registerDocumentVisibleCallback};