Symbol.dispose is undefined when calling vm.runInNewContext

[cesaryuan]

Version

21.2.0

Platform

Microsoft Windows NT 10.0.19045.0 x64

Subsystem

vm

What steps will reproduce the bug?

PS E:\code> node
Welcome to Node.js v21.2.0.       
Type ".help" for more information.
> const vm = require('node:vm')
undefined
> vm.runInNewContext("Symbol.dispose")
undefined
> vm.runInNewContext("Symbol")
[Function: Symbol]

How often does it reproduce? Is there a required condition?

Can be reproduced stably

What is the expected behavior? Why is that the expected behavior?

Symbol.dispose should not be undefined. Because it is avaliable in globally, so it should also be avaliable in vm.

What do you see instead?

vm.runInNewContext("Symbol.dispose") outputs undefined.

Additional information

No response

[joyeecheung]

These symbols are polyfilled by Node.js so they are currently only available in Node.js contexts. I guess we can also polyfill it in the vm context, though I am not too fond of the idea of polyfilling something that should be implemented by V8 in the first place..

[aduh95]

For reference, the V8 issue tracking this is https://bugs.chromium.org/p/v8/issues/detail?id=13559

[malthe]

This issue shows up also when running tests using jest – since tests run in a vm context.

Note that for example Symbol.asyncIterator is defined.

[MoLow]

@malthe is the disposable resource a resource created by your code or internally by node?
if you can provide some reproduction, we might come up with a workaround

[malthe]

The disposable resource is created by my code – it's a database connection.

Now, in TypeScript 5.2, this actually works now because of polyfilling. However, in the VM context, this does not work because the symbols aren't defined.

[legendecas]

Please use a proper polyfill library like babel-polyfills or core-js explicit resource-management to get full feature polyfill.

The Symbol.dipose was polyfilled in Node.js for experimental support in built-in classes. But this was released without hiding behind an experimental flag. The current implementation of explicit resource management proposal in Node.js is incomplete.

I don't think there is anything we can do like hiding the feature with experimental flag or emit a warning as it could break existing pioneers depend on this symbol (#54329). Please follow https://issues.chromium.org/issues/42203506 for future implementation status in V8.

[legendecas]

Fixed in 9d7cd9b with cli flag --js-explicit-resource-management.