JavaScript中的面向对象 类

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一、开篇
        
众所周之，JavaScript
是面向对象的语言。JavaScript
的对象有三种：本地对象、内置对象、自定义类的对象。
其中本地对象和内置对象都是独立于宿主由ECMAScript
实现的。这里所说的本地对象和内置对象