Create javascript object with string type key

I want to create an object some thing like this

var key = "key";
var obj={};
obj[key] = "value";

My required output is

{ "key":"valie"}

Key type must be string because i have keys like #12:5 , #12:89 ( orientDB ids ). REASON:- Because embeddedList of orientDB is not accepting any key without quotes.

Thanks