Is it possible to create a "weak reference" in javascript?
Is there any way in javascript to create a "weak reference" to another object? Here is the wiki page describing what a weak reference is. Here is another article that describes them in Java. Can anyone think of a way to implement this behavior in javascript?
There is no language support for weakrefs in JavaScript. You can roll your own using manual reference counting, but not especially smoothly. You can't make a proxy wrapper object, because in JavaScript objects never know when they're about to be garbage-collected.
So your 'weak reference' becomes a key (eg. integer) in a simple lookup, with an add-reference and remove-reference method, and when there are no manually-tracked references anymore then entry can be deleted, leaving future lookups on that key to return null.
This is not really a weakref, but it can solve some of the same problems. It's typically done in complex web applications to prevent memory leakage from browsers (typically IE, especially older versions) when there is a reference loop between a DOM Node or event handler, and an object associated with it such as a closure. In these cases a full reference-counting scheme may not even be necessary.
在NodeJS上运行JS时，可以考虑https://github.com/TooTallNate/node-weak。
Just for reference; JavaScript doesn't have it, but ActionScript 3 (which is also ECMAScript) does. Check out the constructor parameter for Dictionary.
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