1 function testObject(object){
 2     if(!typeof object == "object")
 3         return;
 4
 5     console.log("object.constructor: " + object.constructor.toString());
 6
 7     if(object.prototype){ //false, 对象没有prototype属性
 8         console.log("object.prototype.constructor: " + object.prototype
 9                     .toString());
10     }
11
12     if(object.__proto__){ //通过内部不可见指针__proto__找到原型对象; 这里运行环境Node,这个属性可见
13         console.log("object.__proto__.constructor: " + object.__proto__.constructor.toString());
14         console.log("__proto__ is not Null");
15         console.log("object.__proto__: " + object.__proto__.toString()); //BasicObject实例的原型是一个Object,而不是null
16     }
17
18     console.log("object.constructor.prototype: " + object.constructor.prototype.name);
19
20     if(object.name){
21         console.log("object.name: " + object.name);
22     }
23
24     if(object instanceof object.constructor)
25         console.log("instanceof True");
26     else
27         console.log("instanceof False");
28 }
29
30 //test 1
31 console.log("Test 1: ");
32 function BasicObject(){
33     console.log("new BasicObject()");
34     this.name = "BasicObject";
35 }
36
37 var obj = new BasicObject();
38 testObject(obj);
39 if(obj.isPrototypeOf(obj)){
40     console.log("prototype is itself");
41 }
42 console.log("BasicObject.prototype: "+BasicObject.protoype); //undefined
43
44 //test 2
45 console.log("Test 2: ");
46 function ProtoObject(){
47     console.log("new ProtoObject()");
48 //    this.name = "ProtoObject";
49 }
50 ProtoObject.prototype = new BasicObject();
51 //console.log("prototype: "+ProtoObject.prototype.toString());
52
53 testObject(new ProtoObject());
54
55 //test 3
56 console.log("Test 3: ");
57 function ConstructorObject(){
58     console.log("new ConstructorObject()");
59     this.constructor = ConstructorObject;
60 }
61 ConstructorObject.prototype = new BasicObject();
62
63 testObject(new ConstructorObject());
64
65 //test null
66 console.log("Test null: ");
67 if(null === null){ // is true
68     console.log("null === null");
69 }
70 if(!null){
71     console.log("null is false");
72 }

Test 1:
new BasicObject()
object.constructor: function BasicObject(){console.log("new BasicObject()");this.name = "BasicObject";
}
object.__proto__.constructor: function BasicObject(){console.log("new BasicObject()");this.name = "BasicObject";
}
__proto__ is not Null
object.__proto__: [object Object]
object.constructor.prototype: undefined
object.name: BasicObject
instanceof True
BasicObject.prototype: undefined
Test 2:
new BasicObject()
new ProtoObject()
object.constructor: function BasicObject(){console.log("new BasicObject()");this.name = "BasicObject";
}
object.__proto__.constructor: function BasicObject(){console.log("new BasicObject()");this.name = "BasicObject";
}
__proto__ is not Null
object.__proto__: [object Object]
object.constructor.prototype: undefined
object.name: BasicObject
instanceof True
Test 3:
new BasicObject()
new ConstructorObject()
object.constructor: function ConstructorObject(){console.log("new ConstructorObject()");this.constructor = ConstructorObject;
}
object.__proto__.constructor: function BasicObject(){console.log("new BasicObject()");this.name = "BasicObject";
}
__proto__ is not Null
object.__proto__: [object Object]
object.constructor.prototype: BasicObject
object.name: BasicObject
instanceof True
Test null:
null === null
null is false

 1 function ObjA(){}
 2
 3 function ObjB(){
 4     this.constructor = ObjB;
 5 }
 6 ObjB.prototype = new ObjA();
 7
 8 var objA = new ObjA();
 9 var objB = new ObjB();
10
11 if(objA instanceof Object)
12     console.log("objA instanceof Object is true");
13 if(objA instanceof ObjA)
14     console.log("objA instanceof ObjA is true");
15
16 if(objB instanceof Object)
17     console.log("objB instanceof Object is true");
18 if(objB instanceof ObjB)
19     console.log("objB instanceof ObjB is true");
20 if(objB instanceof ObjA)
21     console.log("objB instanceof ObjA is true");

objA instanceof Object is true
objA instanceof ObjA is true
objB instanceof Object is true
objB instanceof ObjB is true
objB instanceof ObjA is true