日期:2014-05-16  浏览次数:20378 次

[原]JavaScript学习笔记(六.继承)

1.单继承,使用call()方法

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	//父类
	function Father(name,age)
	{	
		this.Name = name;
		this.Age = age;
		this.Intro = function()
		{
			alert("hello, I am" + this.Name);	
		}
	}
	
	//子类
	function Child(name,age)
	{
		Father.call(this,name,age);//实现继承!并且调用父类的构造方法,this是当前对象		
       //      Father.apply(this, new Array(name,age));	//跟call一样的功能

		this.Code = function()
		{
			alert("I am coding");
		}
	}

	var father = new Father("father",50);
	var child = new Child("child",23);
	
	father.Intro();
	child.Intro();	//子类调用继承自父类的方法
	child.Code();	//子类调用自己的方法

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2.单继承?

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//父类
	function Father(name,age)
	{	
		this.Name = name;
		this.Age = age;
		this.Intro = function()
		{
			alert("hello, I am" + this.Name);	
		}
	}
	
	//子类
	function Child(name,age)
	{
		this.Constructer = Father;	//指定方法为上面那个父类的那个方法,跟下面的方法合起来实现继承
		this.Constructer(name,age);  //调用该方法:注意调用的时候,是Child对象调用,那么调用完,Child的2个属性也就赋值了,而且多了1个方法
		delete this.constructor; // 删除这个方法,是因为不想覆盖父类的相关方法和属性?
			
		this.Code = function()
		{
			alert("I am coding");
		}
	}

	var father = new Father("father",50);
	var child = new Child("child",23);
	
	father.Intro();
	child.Intro();	//子类调用继承自父类的方法
	child.Code();	//子类调用自己的方法

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3.多继承

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//父类1
function Father(name,age)
{	
	this.Name = name;
	this.Age = age;
	this.Intro = function()
	{
		alert("hello, I am" + this.Name);	
	}
}
//父类2
function Father_2(pay)
{
	this.Pay = pay;
	this.showPay = function()
	{
		alert("your pay is " + this.Pay);
	}
}
//子类
function Child(name,age,pay)
{
	this.Constructer = Father;	//指定方法为上面那个父类的那个方法
	this.Constructer(name,age);  //调用该方法:注意调用的时候,是Child对象调用,那么调用完,Child的2个属性也就赋值了,而且多了1个方法
	delete this.Constructor; // 删除这个方法,是因为不想覆盖父类的相关方法和属性?
		
	this.Constructer2 = Father_2;
	this.Constructer2(pay);
	delete this.Constructer2;	
	
	this.Code = function()
	{
		alert("I am coding");
	}
}

var father = new Father("father_1",50);	
var fater_2 = new Father_2(5000);		
var child = new Child("zxh",23,10000);  //I am coding. 

father.Intro();			//hello, I am father'_1
child.Intro();			//调用从第一个父类继承的方法	hello,I am zxh. 
child.Code();			//I am coding							
child.showPay();		//调用从第二个父类继承的方法 your pay is 10000

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4.多继承2


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//父类构造方法
	function Father(name,age)
	{
		this.Name = name;
		this.Age = age;
	}
	
	//父类的方法
	Father.prototype.Intro = function()
	{
		alert("I am father");
	}
	
	//子类构造方法
	function Child(name,age)
	{
		Father.call(this,name,age);	//调用父类构造方法,得到各个属性
	}
	
	Child.prototype = new Father();  //实现继承

	//定义子类自己的方法
	Child.prototype.Code = function()
	{
		alert("I am coding !");
	}
	
	//覆盖父类的方法[如果不指定上面的继承,其实也就相当与自己新定义一个一样]
	Child.prototype.Intro = function()
	{
		alert("I am " + this.Name);
	}
	
	var father = new Father();
	var child = new Child("zxh",23);
	father.Intro(); //父类调用自身方法
	child.Intro();  //子类调用覆盖父类的方法
	child.Code();	//子类调用自己定义的方法

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