是否是“循环”的参考被视为“可达性”。对于弱地图？ [英] Would a "circular" reference be treated as "reachability" for a WeakMap?

问题描述

function f() {
  const w = new WeakMap();
  const o = {};

  w.set(o, { v: o });

  return w;
}

const weakMap = f();

对于给定的代码，唯一的 weakMap 项目被视为可达？因此，它是否会被垃圾收集？

For the given code, would the only weakMap item considered as reachable or not? Hence, will it be garbage collected or not?

PS：这个问题是从规范的角度提出的，而不是特定的实现。

PS: This question is asked from the perspective of the specification, not particular implementations.

推荐答案

引用 WeakMap 对象部分，

Quoting WeakMap Objects section,

如果一个对象被用作WeakMap键/值对的键只能通过跟随在该WeakMap内开始的一系列引用来访问，然后该键/值对不可访问并自动从WeakMap中删除。

If an object that is being used as the key of a WeakMap key/value pair is only reachable by following a chain of references that start within that WeakMap, then that key/value pair is inaccessible and is automatically removed from the WeakMap.

在你的情况下，达到 o 的唯一方法是从<$ c中的一个键开始$ c> weakMap ，因为没有外部引用它。因此，它将被视为无法访问。

In your case, the only way to reach o would be to start from one of the keys in the weakMap, as there is no external references to it. So, it would be considered as inaccessible.

WeakMap实现必须检测并删除此类键/值对以及任何相关资源。

WeakMap implementations must detect and remove such key/value pairs and any associated resources.

因此，它最终会被垃圾收集。

So, it would be eventually garbage collected.

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