diff --git a/src/js/lib/helper.js b/src/js/lib/helper.js
index a72f2e5..a9f0163 100644
--- a/src/js/lib/helper.js
+++ b/src/js/lib/helper.js
@@ -10,7 +10,7 @@ var toInt = exports.toInt = function (x) {
 var clone = exports.clone = function (obj) {
   if (!obj) {
     return null;
-  } else if (obj.constructor === Array) {
+  } else if (Array.isArray(obj)) {
     return obj.map(clone);
   } else if (typeof obj === 'object') {
     var result = {};