Question

Creates a new sequence with every unique element from this one appearing exactly once (i.e., with duplicates removed).

Signature

Sequence.uniq = function(keyFn) { /*...*/ }

Sequence.uniq = function uniq(keyFn) {
  return new UniqueSequence(this, keyFn);
}

Name	Type(s)	Description
keyFn	Function?	An optional function to produce the key for each object. This key is then tested for uniqueness as opposed to the object reference.
returns	Sequence	The new sequence.

Examples

Lazy([1, 2, 2, 3, 3, 3]).uniq() // sequence: [1, 2, 3]
Lazy([{ name: 'mike' }, 
{ name: 'sarah' }, 
{ name: 'mike' }
]).uniq('name')
// sequence: [{ name: 'mike' }, { name: 'sarah' }]

Benchmarks

function randomOf(array) {
  return function() {
return array[Math.floor(Math.random() * array.length)];
  };
}

var mostUnique = Lazy.generate(randomOf(_.range(100)), 100).toArray(),
someUnique = Lazy.generate(randomOf(_.range(50)), 100).toArray(),
mostDupes  = Lazy.generate(randomOf(_.range(5)), 100).toArray();

Lazy(mostUnique).uniq().each(Lazy.noop) // lazy - mostly unique elements
Lazy(someUnique).uniq().each(Lazy.noop) // lazy - some unique elements
Lazy(mostDupes).uniq().each(Lazy.noop)  // lazy - mostly duplicate elements
_.each(_.uniq(mostUnique), _.noop)      // lodash - mostly unique elements
_.each(_.uniq(someUnique), _.noop)      // lodash - some unique elements
_.each(_.uniq(mostDupes), _.noop)       // lodash - mostly duplicate elements

Implementation	mostly unique elements	some unique elements	mostly duplicate elements
lazy
lodash

Run performance benchmarks