unique.js

// in place array unique

function unique (arr) {
  var i = 0;
  var end = arr.length - 1;
  
  while (i < end) {
    var item = arr[i];
    var index = arr.lastIndexOf(item, end);
    if (index > i) {
      arr[i] = arr[end];
      end -= 1;
    } else {
      i += 1;
    }
  }
  
  arr.length = end + 1;
  
  return arr;
}