JavaScript でのクラスとインスタンスの実装メソッド

function Animal() {  
 this.name = "animal";  
 }  
 Animal.prototype.makeSound = function() {  
 console.log("animal sound");  
 }  
[Function]  
 var animal1 = new Animal();  
 animal1.name;  
'animal'  
 animal1.makeSound();  
animal sound

function Point(x, y) {  
 this.x = x;  
 this.y = y;  
 }  
 Point.prototype = {  
 method1: function() { console.log("method1"); },  
 method2: function() { console.log("method2"); },  
 }  
{ method1: [Function], method2: [Function] }  
 var point1 = new Point(10, 20);  
 point1.method1();  
method1  
 point1.method2();  
method2

var Animal = {  
 name: "animal",  
 makeSound: function() { console.log("animal sound"); },  
 }  
 var animal2 = Object.create(Animal);  
 animal2.name;  
'animal'  
 console.log(animal2.name);  
animal  
 animal2.makeSound();  
animal sound

var Animal = {  
 init: function() {  
 var animal = {};  
 animal.name = "animal";  
 animal.makeSound = function() { console.log("animal sound"); };  
 return animal;  
 }  
 };  
 var animal3 = Animal.init();  
 animal3.name;  
'animal'  
 animal3.makeSound();  
animal sound

var Cat = {  
 init: function() {  
 var cat = Animal.init();  
 cat.name2 = "cat";  
 cat.makeSound = function() { console.log("cat sound"); };  
 cat.sleep = function() { console.log("cat sleep"); };  
 return cat;  
 }  
 }  
 var cat = Cat.init();  
 cat.name; // 'animal'  
 cat.name2; // 'cat'  
 cat.makeSound(); // 类似于方法的重载  
cat sound  
 cat.sleep();  
cat sleep

var Animal = {  
 init: function() {  
 var animal = {};  
 var sound = "private animal sound"; // 私有属性  
 animal.makeSound = function() { console.log(sound); };  
 return animal;  
 }  
 };  
 var animal4 = Animal.init();  
 Animal.sound; // undefined 私有属性只能通过对象自身的方法来读取.  
 animal.sound; // undefined 私有属性只能通过对象自身的方法来读取  
 animal4.makeSound();  
private animal sound

var Animal = {  
 sound: "common animal sound",  
 init: function() {  
 var animal = {};  
 animal.commonSound = function() { console.log(Animal.sound); };  
 animal.changeSound = function() { Animal.sound = "common animal sound changed"; };  
 return animal;  
 }  
 }  
 var animal5 = Animal.init();  
 var animal6 = Animal.init();  
 Animal.sound; // 可以视为类属性  
'common animal sound'  
 animal5.sound; // 实例对象不能访问类属性  
undefined  
 animal6.sound;  
undefined  
 animal5.commonSound();  
common animal sound  
 animal6.commonSound();  
common animal sound  
 animal5.changeSound(); // 修改类属性  
undefined  
 Animal.sound;  
'common animal sound'  
 animal5.commonSound();  
common animal sound  
 animal6.commonSound();  
common animal sound