close websocket before unload

htdocs/portal/index.html

@@ -626,6 +626,12 @@
 -->
 <script type="text/javascript">
 
+	$(window).on('beforeunload', function() {
+		if (socket) {
+			socket.close();
+		}
+	});
+
 	function auto_update_calls() {
 		var x = $('#auto_update_calls')[0];
 		if (typeof x != "undefined" && x.checked) {