diff --git a/kfet/static/kfet/js/kfet.api.js b/kfet/static/kfet/js/kfet.api.js
index 7836fcb9..cc499c57 100644
--- a/kfet/static/kfet/js/kfet.api.js
+++ b/kfet/static/kfet/js/kfet.api.js
@@ -525,15 +525,15 @@ class Formatter {
         var prefix_prop = options.prefix_prop !== undefined ? options.prefix_prop : '.';
         var prefix_attr = options.prefix_attr !== undefined ? options.prefix_attr : '';
 
-        for (var i in props) {
-            var selector = prefix_prop + props[i];
-            var html = options.empty_props ? '' : this.get_prop(object, props[i]);
+        for (let prop of props) {
+            var selector = prefix_prop + prop;
+            var html = options.empty_props ? '' : this.get_prop(object, prop);
             $container.find( selector ).html( html );
         }
 
-        for (var i in attrs) {
-            var name = prefix_attr + attrs[i];
-            var value = options.empty_attrs ? '' : this.get_attr(object, attrs[i]);
+        for (let attr of attrs) {
+            var name = prefix_attr + attr;
+            var value = options.empty_attrs ? '' : this.get_attr(object, attr);
             $container.attr( name, value );
         }