javascript继承小工具

这是YUI库的继承方案. 详见: 点击打开链接

<script type="text/javascript">
var Class = {
	extend:function(subClass,superClass){
		var F = function(){};
		F.prototype = superClass.prototype;
		subClass.prototype = new F();			
		subClass.prototype.constructor = subClass;
		
		subClass.superclass = superClass.prototype;
		if(superClass.prototype.constructor == Object.prototype.constructor) {
			superClass.prototype.constructor = superClass;
		}
	}
	/**
	 * 调用父类的构造函数
	 * @param subClass 子类函数名
	 * @param subInstance 子类对象引用
	 */
	,callSuper:function(subClass,subInstance){
		var argsArr = [];
	
		for(var i=2,len=arguments.length; i<len; i++) {
			argsArr.push(arguments[i]);
		}	
		
		subClass.superclass.constructor.apply(subInstance, argsArr);  
	}
	/**
	 * 子类中调用父类的函数
	 * @param subClass 子类函数名
	 * @param subInstance 子类对象引用
	 * @param methodName 父类方法名
	 */
	,runSuperMethod:function(subClass,subInstance,methodName) {
		return subClass.superclass[methodName].call(subInstance);
	}

};

// Demo
// 声明父类
var Person = function(param){
	this.name = param.name;
	this.age = param.age;
}
Person.prototype.sayName = function(){
	alert("My name is " + this.name);
}
Person.prototype.sayAge = function(){
	alert("My age is " + this.age);
}
Person.prototype.getAge = function(){
	return this.age;
}

// 声明子类
var Man = function(param){
	// 调用父类的构造函数
	Class.callSuper(Man,this,param);
}
// 继承父类
Class.extend(Man,Person);

// 覆盖父类的sayAge方法
Man.prototype.sayAge = function(){
	alert(this.name + "'s age is " + this.age);
}
// 覆盖父类的方法,并且调用父类原来的方法
Man.prototype.getAge = function(){
	// 先调用父类方法返回年龄
	var age = Class.runSuperMethod(Man,this,'getAge');
	// 年龄+1
	alert(this.name + "'s age is " + (age + 1));
}

// 测试
var man = new Man({name:"Jim",age:22});	
man.sayName(); // 这里调用父类的方法
man.sayAge();  // 这里调用自己的方法
man.getAge();  
</script>