Javascript闭包在堆或堆栈？ [英] Javascript closures on heap or stack?

问题描述

JavaScript（根据标准）在哪里存储closures：heap或stack？

闭包有第三个显式位置吗？

Where does JavaScript (according to the standard) store closures: heap or stack?
Is there a third explicit place for closures?

推荐答案

最后，它是运行时的实现细节。 请参阅Phoenix链接

In the end it is an implementation detail of the runtime. See Phoenix link

对于实现，为了在上下文被销毁之后存储局部变量，基于栈的实现不再适合（因为它违背基于栈的结构的定义）。因此，在这种情况下，使用垃圾收集器（GC）和引用计数，将父上下文的闭包数据保存在动态存储器分配（在堆，即基于堆的实现）中。这种系统的速度不如基于堆栈的系统有效。然而，实现可能总是优化它：在解析阶段找出是否在函数中使用自由变量，并且根据这个决定 - 将数据放入堆栈或堆。

As to implementations, for storing local variables after the context is destroyed, the stack-based implementation is not fit any more (because it contradicts the definition of stack-based structure). Therefore in this case closured data of the parent context are saved in the dynamic memory allocation (in the "heap", i.e. heap-based implementations), with using a garbage collector (GC) and references counting. Such systems are less effective by speed than stack-based systems. However, implementations may always optimize it: at parsing stage to find out, whether free variables are used in function, and depending on this decide — to place the data in the stack or in the "heap".

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