Support PropertyDefinition

[fisker]

babel/babel#12370

[fisker]

babel switched type back to ClassProperty by default, but it's in estree spec, wthis will still needed someday.

[JLHwung]

Yeah, I plan to enable it by default in Babel 8. Unfortunately we could not enable it on 7.13 since many eslint plugins still depend on Babel AST.

[fisker]

I checked the babel PR above, seems it use eslint as babel plugin in test, how do I enable classFeatures in @babel/eslint-parser? So I can test with the new tree.

[JLHwung]

You can pin @babel/eslint-parser to 7.13.0. In the future it can be toggled on by BABEL_8_BREAKING=true env.

[fisker]

@JLHwung Do you think we can add an option for it in @babel/eslint-parser? Maybe through parseOptions.

I think this can help other eslint plugins easily test/prepare for both these two node types.

[sindresorhus]

@JLHwung ^

[JLHwung]

@sindresorhus Thanks for the ping!

The upstream Babel issue has been resolved. See babel/babel#12891 for an example config enabling the PropertyDefinition in @babel/eslint-parser.

[sindresorhus]

@fisker Is this ready to be merged?