object prototype hasownproperty call

); // Jack; value assigned by the instance; var box2 = new Box (); console. log (box2.name); // Lee; Value in the prototype; not modified by box1; // if you want box1 to continue accessing the value in the prototype, you can delete the attributes in the constructor. delete box1.name; // delete the attributes of the instance. console. log (box1.name); // Lee; Original Value in the

per1 and per2, each instance of Person (per1 and per2) contains a pointer to the prototype object of the constructor (Person. The ECMA-262 version 5th named the pointer [[Prototype]. Therefore, the pointer in the instance only points to the prototype, not the constructor. Although there is no standard method to direct

); // Jack; value assigned by the instance; var box2 = new Box (); console. log (box2.name); // Lee; value in the prototype; not modified by box1; // If you want box1 to continue accessing the value in the prototype, you can delete the attributes in the constructor. delete box1.name; // delete the attributes of the instance. console. log (box1.name); // Lee; original value in the

above the instance, the prototype object pointed to by the instance's __proto__ pointer continues to be looked up, and if not found, the value is undefined.Console.log (Obj1.showusername ()); GhostwuConsole.log (Obj2.showusername ()); WeizhuangThere is no showusername this method on Obj1,obj2, so the Showusername method on Createobj.prototype prototype

"; Cat.prototype.eat = function () {alert ("Eat Mouse")}; var cat1 = new Cat ("Da Mao", "Yellow"); var cat2 = new Cat ("Er Mao", "Black"); Alert (Cat.prototype.isPrototypeOf (CAT1)); True to determine if the CAT1 object is a prototype prototype alert (Cat.prototype.isPrototypeOf (CAT2));//true Determines if Cat2

(Box1.name); Lee; The value in the prototype; Bo1.name = ' Jack '; Console.log (Box1.name); Jack; The value assigned by the instance itself; var box2 = new Box (); Console.log (Box2.name); Lee; The value in the prototype; not modified by box1; If you want Box1 to continue accessing the values in the prototype, you can construc

remember these ideas.The following topics are discussed in this chapter: Each function has a prototype property, and it contains an object. Adds an attribute to prototype. Use the attributes that are added to the prototype. The difference between the function's own properties and the

not found, the value is Undefined.console.log (Obj1.showusername ()); Ghostwuconsole.log (Obj2.showusername ()); Weizhuang There is no showusername this method on the obj1,obj2, so it will follow the __proto__ Find the Showusername method on the Createobj.prototype prototype object if the Showusername on the Createobj.prototype prototype

between the RR person constructor, the prototype property of the person, and the two instances that the person has existing. Here, the person *prototype points to the prototype object, and the Person.prototype.constructor Fork refers back to the person. In addition to containing the Cons t,ruct or property, the

instance of B, and the prototype of B is also an instance of a.It's very useful to have someone else's notes.1. Reference types in the prototype chain.2. Prototype chain do not rely on each other, the GC is not so kind to help you create a temporary storage area.1 function base () {This.arr = [];}function sub () {}Sub.prototype= new Base ();var a = new sub ();va

constructor property, the prototype object includes additional properties that were added later. Each instance of person--person1 and Person2 contains an internal property that points only to Person.prototype; They have no direct relation to the constructor function . In addition, it is important to note that although none of the two instances contain properties and methods, we can

Person ();Person. showName ();The above Code uses a prototype instead of a constructor to initialize an object. This is done and is directly defined in the constructor.What are the differences between attributes? **The property inheritance method defined in the constructor is different from that defined in the prototype. The sub-

. func = function () {console. log (this. a + this. b); // this} can be used here; // cosole. log (this. a); // here this is the // obj in the window. func (); Factory Mode // Instantiate objects in a centralized manner. The factory mode var createObj = function (a, B) {var obj = new Object (); obj. a = a; obj. B = B; obj. func = function () {return this. a + this. B ;}; return obj ;}var obj1 = createObj ("a1", "b1"); var obj2 = createObj ("a2", "b2"

. showName ();The above Code uses a prototype instead of a constructor to initialize an object. This is done and is directly defined in the constructor.What are the differences between attributes?**The property inheritance method defined in the constructor is different from that defined in the prototype. The sub-object

, we first created a Parent class Parent and added the showParentValue method to its prototype. Then we create a Child subclass and inherit it by pointing the prototype chain of the subclass to the parent class. /** Key code for inheritance **/Child. prototype = new Parent (); Then add the showChildValue Method to the prototy