Creates an array of values by running each element in collection through iteratee. The iteratee is invoked with three arguments:
(value, index|key, collection).

Many lodash methods are guarded to work as iteratees for methods like _.every, _.filter, _.map, _.mapValues, _.reject, and _.some.

The guarded methods are:
ary, callback, curry, curryRight, drop, dropRight, every, fill, invert, parseInt, random, range, slice, some, sortBy, take, takeRight, template, trim, trimLeft, trimRight, uniq, and words

function square(n) {
  return n * n;
}

_.map([1, 2], square);
// => [3, 6]

_.map({ 'a': 1, 'b': 2 }, square);
// => [3, 6] (iteration order is not guaranteed)

var users = [
  { 'user': 'barney' },
  { 'user': 'fred' }
];

// using the `_.property` callback shorthand
_.map(users, 'user');
// => ['barney', 'fred']