Minor ES6 improvements

Change-Id: Ibf956915d1b7769dc5cc22a870f4484f492da723
diff --git a/dev/js/src/panel.js b/dev/js/src/panel.js
index c2c2293..498a7f1 100644
--- a/dev/js/src/panel.js
+++ b/dev/js/src/panel.js
@@ -8,14 +8,14 @@
 
     // TODO:
     //   Support classes
-    create : function (viewpos) {
+    create : function (viewpos = 'up') {
       return Object.create(this)._init(viewpos);
     },
 
     _init : function (viewpos) {
       this.views = [];
 
-      this._viewpos = (viewpos == 'down' ? viewpos : 'up');
+      this._viewpos = viewpos;
 
       
       /**