Merge pull request #603 from luckyorange/master

Replaced obj.constructor with Array.isArray

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 = {};