跟我一块儿动手写js库--JavaScript之继承与多态

继承的话我这里主要是传统的原型继承方式。关于原型继承，这个在网上已经有现有的轮子了（参考了慕课网Bosn老师的JavaScript深刻浅出一篇的原型继承的视频讲解），我就站在巨人的肩上给稍微改动了下了

Object.prototype.extends = function(SuperClass) {
	
	if(!Object.create) {
		Object.create = function(proto) {
			function F() {
				
				F.prototype = proto;
				return new F;
			}
		}
	}
	var oldPrototype = this.prototype;
	this.prototype = Object.create(SuperClass.prototype);
	
//	this.prototype.constructor = SuperClass;
	for(key in oldPrototype) {
		oldPrototype[key] !=undefined && (this.prototype[key]=oldPrototype[key]);
	}
	this.prototype.__parent__ = SuperClass;
};
Object.prototype.super = function() {
	
	var param = arguments[0];
	var arg = arguments;
	
	while(param) {
		
		if(!param.callee) {
			break;
		}
		arg = param;
		param = param[0];
	}

	var parent = this;
	
	while(parent) {
		
		for(var key in parent) {//首次子类调用该方法
			
			if(arguments[0].callee == parent[key]) {//找到对应父类
				arg.callee = arguments[0].callee;
				parent.__parent__.prototype[key].apply(this, arg);
				return;
			}
		}
		for(var key in parent.prototype) {
			
			if(arguments[0].callee == parent.prototype[key]) {//找到对应父类
				arg.callee = arguments[0].callee;
				parent.prototype.__parent__.prototype[key].apply(this, arg);
				return;
			}
		}
		parent = parent.__parent__;
	}
};

Object.defineProperties(Object.prototype, {
	'extends': {
		enumerable: false,
		writable: false
	},
	'super': {
		enumerable: false,
		writable: false
	}
});

使用例子：

var Person = function() {};

Person.prototype = {
    say: function() {
        console.log("person say");
    }
};

var Father = function() {};

Father.prototype = {
    say: function() {
        this.super(arguments);
        console.log("father say");
    }
}

Father.extends(Person);

var Son = function() {};

Son.prototype = {
    say: function() {
        this.super(arguments);
        console.log("son say");
    }
}

Son.extends(Father);

var son = new Son();
son.say();

var Daughter = function() {};

Daughter.prototype = {
    say: function() {
        this.super(arguments);
        console.log("daughter say");
    }
}

Daughter.extends(Father);

var daughter= new Daughter();
daughter.say();

/************* 打印结果 ***************/

person say
father say
son say
person say
father say
daughter say

多态主要是在方法里面经过调用this.super(arguments)就会自动向上调用父类的同名方法。以上即是本次的js代码库分享，但愿你们多多指点、多多评论，也但愿我之后能给你们带来更多有用的库方法或者类。欢迎转载，原文出处 http://www.javashuo.com/article/p-adskjsfx-dw.html