Javascript核心

在学习Javascript的prototype与__proto__区别时，发现了这样一篇介绍javascript核心的好文章。原文：javascript the core. 本想阅读后好好整理翻译下，不过网上已经有很好的翻译文章，就此省略，链接在此。这里只作简单摘要：

javascript核心概念：

1. An Object 对象

   An object is a collection of properties and has a single prototype object. The prototype may be either an object or the null value.

2. A prototype chain 原型链

   A prototype chain is a finite chain of objects which is used to implement inheritance and shared properties.

3. Constructor 构造函数
4. Exceution context stack 执行上下文栈
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6. Exceution content 执行上下文
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8. Variable object 变量对象

   A variable object is a container of data associated with the execution context. It’s a special object that stores variables and function declarations defined in the context.

9. Activation Object 活动对象
10. Scope chain 作用域链

    A scope chain is a list of objects that are searched for identifiers appear in the code of the context.

11. Closures 闭包

    A closure is a combination of a code block (in ECMAScript this is a function) and statically/lexically saved all parent scopes. Thus, via these saved scopes a function may easily refer free variables.

12. this 

    A this value is a special object which is related with the execution context. Therefore, it may be named as a context object (i.e. an object in which context the execution context is activated).
    
    a this value is a property of the execution context, but not a property of the variable object.