// Return new array with duplicate values removed
Array.prototype.unique =
  function() {
    var a = [];
    var l = this.length;
    for(var i=0; i<l; i++) {
      for(var j=i+1; j<l; j++) {
        // If this[i] is found later in the array
        if (this[i] === this[j])
          j = ++i;
      }
      a.push(this[i]);
    }
    return a;
  };