After console.log(item) I got following object.
console.log(item)
Object {_value: \"106\", _id: \"opt_zXtP8TOfW2zteOgDIJQDI6Bxx3xSTkl5\", _class: \"selected\", _
You're ignoring the underscore. value and _value are not the same. You need to use:
value
_value
item["_value"];
Or:
item._value;