JavaScript Object learning notes (2)-Simulation Implementation

1. instance attributes, instance methods and class attributes, and class methods

Function circle (r ){

This. redius = r; // redius attribute instance attributes, that is, each instance object of this type has the copy attribute.

}

Circle. Pi = 3.14; // P is a class attribute of the circle class and has nothing to do with the instance.

Circle. Prototype. Area = function () {return circle. Pi * This. redius * This. redius}; // area is an instance method that references the class property pi

Circle. init = function () {return new circle (1);} Init () is a class method used to create a circle with a radius of 1

Non-static attributes or functions in Java

Class attributes and methods are similar to static attributes or functions in Java.

2. class inheritance

Animals:

Function animal (){

This. type = "animal ";

}

Cat:

Function CAT (name, age ){

This. Name = Name;

This. Age = age;

}

How can we make cat inherit the animal class?

1. constructor binding mode:

Function CAT (name, age ){

Animal. Call (this, [arguments]) // arguments is the passed parameter array. this parameter is the object that calls this function. Here it is cat

This. Name = Name;

This. Age = age;

}

VaR c = new car ('Tom ', 19 );

Console. Log (C. Type );

2. Prototype inheritance mode

Cat. Prototype = new animal (); // reinitialize the original prototype of cat.

Cat. Prototype. constuctor=CAT; // The original prototype has been assigned a new value,PrototypeConstructor does not exist. Therefore, you need to re-specify the constructor value. Here is cat,
Otherwise there is a problem with the inheritance chain.

VaR c = new car ('Tom ', 19 );

Console. Log (C. Type );

In short, we should observe one point in programming if the value of O. prototype is re-assigned:

O. Prototype = {};

Next, assign a value to O. Prototype. constructor:

O. Prototype. constructor = O;