JavaScript functions are a combination of code to be executed and the scope in which to execute them. This combination of code and scope is known as a closure in the computer science literature. All JavaScript functions are closures. These closures are only interesting, however, in the case discussed above: when a nested function is exported outside the scope in which it is defined. When a nested function is used in this way, it is often explicitly called a closure.

 

    When the JavaScript interpreter invokes a function, it first sets the scope to the scope chain that was in effect when the function was defined. Next, it adds a new object, known as the call object (the ECMAScript specification uses the term activation object) to the front of the scope chain. The call object is initialized with a property named arguments that refers to the Arguments object for the function. Named parameters of the function are added to the call object next. Any local variables declared with the var statement are also defined within this object. Since this call object is at the head of the scope chain, local variables, function parameters, and the Arguments object are all in scope within the function. This also means that they hide any properties with the same name that are further up the scope chain, of course.

 

    When no nested functions are involved, the scope chain is the only reference to the call object. When the object is removed from the chain, there are no more references to it, and it ends up being garbage collected.

 

    But nested functions change the picture. If a nested function is created, the definition of that function refers to the call objects because that call object is the top of the scope chain in which the function was defined. If the nested function is used only within the outer function, however, the only reference to the nested function is in the call object. When the outer function returns, the nested function refers to the call object, and the call object refers to nested function, but there are no other references to either one, and so both objects become available for garbage collection.

 

    Things are different if you save a reference to the nested function in the global scope. You do so by using the nested function as the return value of the outer function or by storing the nested function as the property of some other object. In this case, there is an external reference to the nested function, and the nested function retains its reference to the call object of the outer function. The upshot is that the call object for that one particular invocation of the outer function continues to live, and the names and values of the function arguments and local variables persist in this object. JavaScript code cannot directly access the call object in any way, but the properties it defines are part of the scope chain for any invocation of the nested function. (Note that if an outer function stores global references to two nested functions, these two nested functions share the same call object, and changes made by an invocation of one function are visible to invocations of the other function.) 

    昨天去面了家外资公司，很失败。不知道是因为刚放完长假还是其他的什么原因，状态之差简直到了不能想象的地步，整个面试过程中几乎都答非所问，连自己的思想都未能表达清楚，就更别提展示自己的强项了。过程就不打算详说了，记点想的到的东西，将来可以参考参考，然后更好的提高自己吧。

    1、外资和外资之间也是有很大差别的，不一定名气越大薪水越高的公司就越好。今天去的公司名气不大，但是一进去就看到不少老外在和中国方面的员工交流工作方面的事项，而且不是少数几个，是几乎视线内处处都有这样的场景。给我的感觉非常不错，以前虽然也在号称是外资的公司呆过，而且还是号称有几千人且比较有名气的公司，但明显只是批了个外资的皮，挂着羊头卖狗肉。-。-

    2、自己的职场英语还不过关。随便聊聊的时候自我感觉还不错，因为平时美剧看的比较多，说说东扯扯西的，还觉得自己挺溜的，但是一旦听到一些平时很少接触到的职场或者专业相关的英语词汇，就傻眼了。听都这样了，就更别提说了，回答专业问题的时候才发现要用这么些平时很少说的词汇来组织语言、表达自己的思想是多难啊。不过没环境怎么练呢，郁闷... @_@

    3、由于2，所以导致3。我这个人有个缺点，很难一心多用，同一时间只能专著与一件事上。如果我在表达的时候感觉很顺利，那后续的思维肯定极其活跃，闪光点一个接一个的冒出来，感觉就和头脑风暴似的。但是一旦在表达的过程中发生卡壳现象，那后续思维就也会卡壳，会将思考的频道一下子就转到如何才能确切的表达当前思想上去，导致说下一句的时候大脑完全不知道在做什么。sigh，这点以后要好好锻炼锻炼。

    4、平时太依赖IDE和doc还有google了。

 

    暂时就想到这些，下次想到了再补，over。