fake_ecmascript5_methods.js

(function () {
  function define(owner, prop, value) {
    if (typeof owner[prop] !== "function") {
      owner[prop] = value;
    }
  }

  define(Object, "keys", function (object) {
    var k,
        result = [];
    for (k in object) {
      if (Object.prototype.hasOwnProperty.call(object, k))
        result.push(k);
    }
    return result;
  });

  define(Object, "getOwnPropertyDescriptor", function (object, property) {
    var desc = {},
        k,
        tmp = object[property],
        id = {},
        getter = Object.prototype.__lookupGetter__.call(object, property),
        setter = Object.prototype.__lookupGetter__.call(object, property);
    desc.enumerable = Object.keys(object).indexOf(property) >= 0;
    if (getter || setter) {
      desc.getter = getter;
      desc.setter = setter;
    } else {
      desc.value = tmp;
    }
    try {
      object[property] = id;
      if (object[property] === id)
        desc.writable = true;
    } catch (ex) {
      desc.writable = false;
    } finally {
      try {
        object[property] = tmp;
      } catch (ex) {
      }
    }
    try {
      delete object[property];
      desc.configurable = !(property in object);
    } catch (ex) {
      desc.configurable = false;
    } finally {
      try {
        object[property] = tmp;
      } catch (ex) {
      }
    }
    return desc;
  });

  define(Object, "getPrototypeOf", function (object) {
    return object.__proto__;
  });

  define(Array, "isArray", function (object) {
    return Object.prototype.toString.call(object) == "[object Array]";
  });
})();