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closes #2319

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Ilya Kantor 2020-11-29 11:22:53 +03:00
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commit 574dd84b23
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1-js/99-js-misc/01-proxy/article.md
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@ -963,9 +963,13 @@ revoke();
alert(proxy.data); // Error alert(proxy.data); // Error
``` ```
A call to `revoke()` removes all internal references to the target object from the proxy, so they are no longer connected. The target object can be garbage-collected after that. A call to `revoke()` removes all internal references to the target object from the proxy, so they are no longer connected.
We can also store `revoke` in a `WeakMap`, to be able to easily find it by a proxy object: Initially, `revoke` is separate from `proxy`, so that we can pass `proxy` around while leaving `revoke` in the current scope.
We can also bind `revoke` method to proxy by setting `proxy.revoke = revoke`.
Another option is to create a `WeakMap` that has `proxy` as the key the corresponding `revoke` as the value, that allows to easily find `revoke` for a proxy:
```js run ```js run
*!* *!*
@ -980,15 +984,13 @@ let {proxy, revoke} = Proxy.revocable(object, {});
revokes.set(proxy, revoke); revokes.set(proxy, revoke);
// ..later in our code.. // ..somewhere else in our code..
revoke = revokes.get(proxy); revoke = revokes.get(proxy);
revoke(); revoke();
alert(proxy.data); // Error (revoked) alert(proxy.data); // Error (revoked)
``` ```
The benefit of such an approach is that we don't have to carry `revoke` around. We can get it from the map by `proxy` when needed.
We use `WeakMap` instead of `Map` here because it won't block garbage collection. If a proxy object becomes "unreachable" (e.g. no variable references it any more), `WeakMap` allows it to be wiped from memory together with its `revoke` that we won't need any more. We use `WeakMap` instead of `Map` here because it won't block garbage collection. If a proxy object becomes "unreachable" (e.g. no variable references it any more), `WeakMap` allows it to be wiped from memory together with its `revoke` that we won't need any more.
## References ## References