Check performance of detecting arrays in Rhino

detectarray.js

// Original is http://d.hatena.ne.jp/uupaa/20090116/1232051707
var array = [];
var notarray = {};

(function () {
  var S = new Date*1;
  var toString = Object.prototype.toString;
  for (var i = 0; i < 5000000; i++) { ( toString.call(array) === "[object Array]" ) }
  print('Array#Object.prototype.toString.call : ' + (new Date-S));
}());

(function () {
  var S = new Date*1;
  var toString = Object.prototype.toString;
  for (var i = 0; i < 5000000; i++) { ( toString.call(notarray) === "[object Array]" ) }
  print('notArray#Object.prototype.toString.call : ' + (new Date-S));
}());

(function () {
  var S = new Date*1;
  for (var i = 0; i < 5000000; i++) { ( "length" in array ) }
  print('"length" in array : ' + (new Date-S));
}());

(function () {
  var S = new Date*1;
  for (var i = 0; i < 5000000; i++) { ( "length" in notarray ) }
  print('"length" in notarray : ' + (new Date-S));
}());

(function () {
  var S = new Date*1;
  for (var i = 0; i < 5000000; i++) { (array instanceof Array) }
  print('Array#instanceof : ' + (new Date-S));
}());

(function () {
  var S = new Date*1;
  for (var i = 0; i < 5000000; i++) { (notarray instanceof Array) }
  print('notArray#instanceof : ' + (new Date-S));
}());

(function () {
  var S = new Date*1;
  for (var i = 0; i < 5000000; i++) { (Array.isArray(array)) }
  print('Array#Array.isArray : ' + (new Date-S));
}());

(function () {
  var S = new Date*1;
  for (var i = 0; i < 5000000; i++) { (Array.isArray(notarray)) }
  print('notArray#Array.isArray : ' + (new Date-S));
}());

result

Result with Rhino 1.7R3

 TEST                                    | time [ms]
-----------------------------------------+------------
 Array#Object.prototype.toString.call    | 968
 notArray#Object.prototype.toString.call | 816
 "length" in array                       | 180
 "length" in notarray                    | 294
 Array#instanceof                        | 321
 notArray#instanceof                     | 344
 Array#Array.isArray                     | 361
 notArray#Array.isArray                  | 371