Creates an object with the same keys as object and values generated by running each own enumerable property of object through iteratee. The iteratee function is invoked with three arguments: (value, key, object).

var users = {
  'fred':    { 'user': 'fred',    'age': 40 },
  'pebbles': { 'user': 'pebbles', 'age': 1 }
};

_.mapValues(users, function(o) { return o.age; });
// => { 'fred': 40, 'pebbles': 1 } (iteration order is not guaranteed)

// using the `_.property` callback shorthand
_.mapValues(users, 'age');
// => { 'fred': 40, 'pebbles': 1 } (iteration order is not guaranteed)