var p = Object.getPrototypeOf(obj);

var obj = Object.create(p);

var obj = {};
var p = {};

obj.__proto__ = p;
Object.getPrototypeOf(obj) === p // true

var a = {x: 1};
var b = {__proto__: a};
b.x // 1

var o = new Foo();

// 等同于
var o = new Object();
o.__proto__ = Foo.prototype;
Foo.call(o);

var a = { x: 1 };
var b = { __proto__: a };
var c = { __proto__: b };

c.x // 1

var o = {
 a: 2,
 m: function(b) {
  return this.a + 1;
 }
};

var p = Object.create(o);
p.a = 12;

p.m() // 13

function Shape() {
 this.x = 0;
 this.y = 0;
}

Shape.prototype.move = function (x, y) {
 this.x += x;
 this.y += y;
 console.info('Shape moved.');
};
Rectangle构造函数继承Shape。

function Rectangle() {
 Shape.call(this); // 调用父类构造函数
}
// 另一种写法
function Rectangle() {
 this.base = Shape;
 this.base();
}

// 子类继承父类的方法
Rectangle.prototype = Object.create(Shape.prototype);
Rectangle.prototype.constructor = Rectangle;

var rect = new Rectangle();

rect instanceof Rectangle // true
rect instanceof Shape // true

rect.move(1, 1) // 'Shape moved.'

ClassB.prototype.print = function() {
 ClassA.prototype.print.call(this);
 // some code
}

var obj = new Object();

obj.__proto__ === Object.prototype
// true
obj.__proto__ === obj.constructor.prototype
// true

var P = function () {};
var p = new P();

var C = function () {};
C.prototype = p;
var c = new C();

c.constructor.prototype === p // false

C.prototype = p;
C.prototype.constructor = C;

c.constructor.prototype === p // true

var o = new Object();

Object.getPrototypeOf(o) === Object.prototype
// true

Object.getPrototypeOf({ __proto__: null }) === null

vehicle.__proto__ = machine;
car.__proto__ = vehicle;

Array.prototype.p = 'abc';
var a = new Array();

a.__proto__.p // abc
a.constructor.prototype.p // abc

var f = function (){};
var a = {};

f.prototype = a;
var o = new f();

o.__proto__ === a
// true

Object.getOwnPropertyNames(Date)
// ["parse", "arguments", "UTC", "caller", "name", "prototype", "now", "length"]

Object.keys(Date) // []
hasOwnProperty()

Date.hasOwnProperty('length')
// true

Date.hasOwnProperty('toString')
// false

var proto = { p1: 123 };
var o = Object.create(proto);

o.p1 // 123
o.hasOwnProperty("p1") // false

"length" in Date // true
"toString" in Date // true

var o1 = {p1: 123};

var o2 = Object.create(o1,{
 p2: { value: "abc", enumerable: true }
});

for (p in o2) {console.info(p);}
// p2
// p1

for ( var name in object ) {
 if ( object.hasOwnProperty(name) ) {
  /* loop code */
 }
}

function inheritedPropertyNames(obj) {
 var props = {};
 while(obj) {
  Object.getOwnPropertyNames(obj).forEach(function(p) {
   props[p] = true;
  });
  obj = Object.getPrototypeOf(obj);
 }
 return Object.getOwnPropertyNames(props);
}

inheritedPropertyNames(Date)
// ["caller", "constructor", "toString", "UTC", "call", "parse", "prototype", "__defineSetter__", "__lookupSetter__", "length", "arguments", "bind", "__lookupGetter__", "isPrototypeOf", "toLocaleString", "propertyIsEnumerable", "valueOf", "apply", "__defineGetter__", "name", "now", "hasOwnProperty"]

function copyObject(orig) {
 var copy = Object.create(Object.getPrototypeOf(orig));
 copyOwnPropertiesFrom(copy, orig);
 return copy;
}

function copyOwnPropertiesFrom(target, source) {
 Object
 .getOwnPropertyNames(source)
 .forEach(function(propKey) {
  var desc = Object.getOwnPropertyDescriptor(source, propKey);
  Object.defineProperty(target, propKey, desc);
 });
 return target;
}

function M1(prop) {
 this.hello = prop;
}

function M2(prop) {
 this.world = prop;
}

function S(p1, p2) {
 this.base1 = M1;
 this.base1(p1);
 this.base2 = M2;
 this.base2(p2);
}
S.prototype = new M1();

var s = new S(111, 222);
s.hello // 111
s.world // 222