Property not assigned to child class when set by parent

[adi518]

Acknowledgements

• [X] I searched existing issues to avoid duplicates
• [X] I understand this is a place to report a confirmed bug (not seek debugging help)
• [X] I understand this is a collaborative open source project, and relies on community contributions
• [X] I have read and understood the Contribution guide

Minimal reproduction URL

https://stackblitz.com/edit/node-5p2jxx?file=index.ts

Version

v0.0.0

Node.js version

v18.18.0

Package manager

npm

Operating system

macOS

Problem & expected behavior (under 200 words)

• What happened Child class instance property t was set to undefined.
• What I expected Child class instance property t to be set.
• Error stack trace
• Documentation links
• Screenshots

Contributions

• [ ] I will open a pull request for this issue
• [ ] I will support the work financially (any amount helps)

[privatenumber]

Can you make your reproduction minimal?

1 or 2 files if possible.

And remove the types, convert it to JS, and verify it works expectedly in Node.

[adi518]

Done. You now have three commands: start for JS, start-tsx, and start-ts-node, so you can compare them. Btw, I also observed this behavior with SWC, which makes me suspect it's a strict mode thing or a configuration issue.

[privatenumber]

This is happening because of useDefineForClassFields.

TypeScript (and ts-node) sets the target to ES3 by default, which yields this behavior. But tsx sets the target based on your Node.js runtime version.

Read more about it here: https://esbuild.github.io/content-types/#no-type-system