Uncaught TypeError: Object.keys called on non-object while trying to access object

Question

I am trying to access array inside object using Object.keys(obj.arr)); method. If I access array directly like below, then it is giving proper output:

 alert(Object.keys(obj.arr));

but if I pass array name using parameter then it is giving error :

var selected = "arr";
alert(Object.keys(obj.arr));

error : Uncaught TypeError: Object.keys called on non-object 

There is example : DEMO

Answer 1

If you need dynamic property access, you cannot use .value. That is always literally accessing named key of "value". If you want to access property with the key name contained in the variable value you need to use brackets: obj[value]

Fixed demo: http://jsfiddle.net/Lv6TY/7/

console.log("Variable Pass "+Object.keys(groups[selected]));