pull_some_random_elements.js

input = [0,1,2,3,4,5,6,7,8,9]
len = 3

resort = function(input, len) {
  count = len
  while(count--) {
    last = input.length-(len-count)
    id = parseInt(Math.random()*last)
    el = input[id]
    input[id] = input[last]
    input[last] = el
  }
  return input.slice(-len)
}

resort(input, len)