var o = {
 foo : "bar"
 }
 

var o = new Object();
 

var p = Object.create(o);
 

var O = {
 x : 1
 };
function P() {
 this.y = 2;
 }
P.prototype = O;
var t = new P();
 console.log(t);
 console.log('x' in t);//true
 console.log(t.hasOwnProperty('x'));//false
 

var o = {
  foo : 'bar'
}
Object.defineProperty(o, "foo", { writable : false });
o.foo = 'world';
console.log(o.foo);//仍然输出bar

for (p in Array) {
  console.log(p);
}

var book = {
  _year: 2004,
  edition: 1
};
Object.defineProperty(book, "year", {
  get: function () {
    console.log('get year');
    return this._year;
  },
  set: function (newValue) {
    console.log('set year');
    if (newValue > 2004) {
      this._year = newValue;
      this.edition += newValue - 2004;
    }
  }
});
book.year = 2005;//控制台输出‘set year'
console.log(book.year);//控制台输出‘get year'和year的值

function bar(o) {
  var f = function() { return "Hello World!"; }
  o.__proto__ = f.__proto__;
  f.__proto__ = o;
  return f;
}
var o = { x: 5 };
var foo = bar(o);
console.log(foo());
console.log(foo.x);
console.log(typeof foo);//function