Assuming I have the following:
var array =
[
{\"name\":\"Joe\", \"age\":17},
{\"name\":\"Bob\", \"age\":17},
{\"name\":\"Carl\
I've started sticking Underscore in all new projects by default just so I never have to think about these little data-munging problems.
var array = [{"name":"Joe", "age":17}, {"name":"Bob", "age":17}, {"name":"Carl", "age": 35}];
console.log(_.chain(array).map(function(item) { return item.age }).uniq().value());
Produces [17, 35]
.