Array.prototype.sample = (size = 1)->
  dup = @concat()
  [0...size].map ->
    randomNumber = (Math.floor(Math.random() * dup.length))
    dup.splice(randomNumber, 1)[0]
  .filter (item)-> item

console.log [1,2,3,4,5].sample()
console.log [1,2,3,4,5].sample(3)