JavaScript : Count unique items in an array

gistfile1

$.extend({
  countUnique : function(array) {
    var result = [];
    $.each(array, function(i,v) {
      if($.inArray(v, result) == -1) {
        result.push(v); 
      }
    });
    return result.length;
  }
});

var array = [1, 2, 3, 4, 5, 1, 2, 3, 4, 5];

$.countUnique(array);