I've looked at this Stack question, Removing duplicate objects with Underscore for Javascript and that is exactly what I am trying to do, but none of the examples work. In fact I can not get any iterator function to work with _.uniq.

_.uniq([1, 2, 1, 3, 1, 4]);

> [1, 2, 3, 4]

_.uniq([1, 2, 1, 3, 1, 4], false, function(a){ return a===4;});

> [1, 2, 3, 4]

_.uniq([1, 2, 1, 3, 1, 4], true, function(a){ return a===4;});

> [1, 2, 1, 3, 1, 4]

_.uniq([1, 2, 1, 3, 1, 4], false, function(a){ return false;});

> [1, 2, 3, 4]

_.uniq([1, 2, 1, 3, 1, 4], false, function(a){ return true;});

> [1, 2, 3, 4]



var people = [ { name: 'John', age: 20 }, { name: 'Mary', age: 31 }, { name: 'Kevin', age: 20 }]; 

_.uniq(people, false, function(p){ return p.age; });



> [ { age: 20, name: John }, 

    { age: 31, name: Mary },

    { age: 20, name: Kevin } ]

I would do:

_.uniq(_.map(people, function(p){ return p.age; }));

> [20, 31]

but it returns only the mapped value, not the original object.

Any help appreciated. I am using underscore version 1.1.7