【前端学习笔记03】JavaScript对象相关方法及封装

	//Object.create()创建对象
	var obj = Object.create({aa:1,bb:2,cc:'c'});
	obj.dd = 4;
	console.log(obj.cc); // c
	console.log(obj.hasOwnProperty("cc")); //false
	console.log(obj.hasOwnProperty("dd")); // true

   //仿Object.create()方法创建CreateObject函数
	var obj = {aa:1,bb:2,cc:'c'};
	function CreateObject(proto){
		function F(){};
		F.prototype = proto;
		return (new F);
	}
	var newObj = CreateObj(obj);

    //构造函数和原型结合创建对象举例
	function Circle(r){
        this.r = r;
	}
	Circle.prototype.circum = function(){
	    return (2*this.r*Math.PI).toFixed(2);
	}
	Circle.prototype.area = function(){
	    return (Math.pow(this.r,2)*Math.PI).toFixed(2);
	}
	 
	var c = new Circle(3);
	console.log(c.circum());
	console.log(c.area());

	//复制一个对象 
	function copyObj(obj){
		var newObj = {};
		for(key in obj){
			newObj[key] = obj[key];
		}
		return newObj;
	}

	//类继承举例
		//创建父类
		function Father(){
		    this.familyName = 'Zhu';
		    this.money = 20;
		}
		//父类原型
		Father.prototype.have= function(){
		    return 'I have $'+this.money+'.'
		}
		//创建子类
		function Child(){
		    Father.apply(this,arguments);
		    this.toy = 'car';
		}
		//子类原型等于父类构造的新对象
		Child.prototype = new Father();
		//子类的构造函数重定向
		Child.constructor = Child;
		 //子类可创建自己的方法
		Child.prototype.play = function(){
		    return 'I play with a '+this.toy+'.'
		}
		//基于子类创建新对象
		var child = new Child();


	//extend方法 对象扩展
	function extend(target,source){
		for(k in source){
			target[k] = source[k];
		}
		return target;
	}