array.js

function EXArray() {
  var result = [];
  result.__proto__ = EXArray.prototype;
  for (var i = 0, len = arguments.length; i < len; ++i) {
    result[i] = arguments[i];
  }
  return result;
}

// どうせなら仕様の範囲内で
EXArray.prototype = new Array();
EXArray.prototype.constructor = EXArray;

Object.defineProperties(EXArray.prototype, {
  item : {
    value: function item(i) {
      return this[i];
    },
    writable: true,
    configurable: true
  }
});

function assert(msg, bool) {
  print(msg + ': ' + (bool ? 'OK' : 'NG'));
}

function test_hasOwnProperty() {
  var a = new EXArray('a');
  assert('a.hasOwnProperty(0)', a.hasOwnProperty(0));
  a.push('b');
  assert('a.hasOwnProperty(1)', a.hasOwnProperty(1));
  print('a.item(0) is ' + a.item(0));
  assert('a.item(0) == "a"', a.item(0) === 'a');
  assert('a.toString() === "a,b"', a.toString() === 'a,b');
}

function test_instanceof() {
  var a = new EXArray();
  assert('a instanceof Array', (a instanceof Array));
  assert('a instanceof EXArray', (a instanceof EXArray));
}

function test_JSON() {
  var a = new EXArray();
  a.push("a");
  a.push("b");
  assert('JSON.stringify(a)', JSON.stringify(a) === '["a","b"]');
}

function test_toSource() {
  var a = new EXArray();
  a.push("a");
  a.push("b");
  print(a.toSource());
  assert('a.toSource()', a.toSource() === '["a", "b"]');
}

test_hasOwnProperty();
test_instanceof();

(function() {
  for (var key in this) {
    if (key.indexOf('test') === 0 && typeof this[key] === 'function') {
      print('===== ' + key + ' ========');
      this[key]();
    }
  }
})();