ship @babel/standalone source maps

[JLHwung]

Q	A
Fixed Issues?	Address #14179 (comment)
Patch: Bug Fix?
Major: Breaking Change?
Minor: New Feature?
Tests Added + Pass?	Yes
Documentation PR Link
Any Dependency Changes?
License	MIT

Ship @babel/standalone source maps. Previously when @babel/standalone throws an error, the stack trace is barely readable due to minifying. Shipping the source maps and if a website owner hosts such maps, the situation should be improved.

Of course, the source maps will increase the published artifact size. But given that @babel/standalone is meant for browser users. I think it is acceptable.

[liuxingbaoyu]

Can we unify NODE_ENV into BABEL_ENV? There is currently only one place where NODE_ENV is used, and there are more BABEL_ENV.

[nicolo-ribaudo]

Could you open a PR to replace both? 🙏

[liuxingbaoyu]

Yeah. I'll do this after 7.19.0 is released, it's a little messy and I'm worried about causing accidents.

[liuxingbaoyu]

Also maybe we can generate all source maps in development environment? That should make debugging easier for us.

[babel-bot]

Build successful! You can test your changes in the REPL here: https://babeljs.io/repl/build/52850/

[JLHwung]

Also maybe we can generate all source maps in development environment?

Personally I am cool with that because few syntaxes are transformed when I am developing on latest Node.js. With that said, I would not block such PR to add sourcemaps: true to babel-worker.cjs.

[JLHwung]

Hmm I have no idea why GitHub CI is not showing up. I will re-invoke the CI an hour later.

[liuxingbaoyu]

https://www.githubstatus.com/incidents/8gpymn7rystj
lol

[liuxingbaoyu]

CI is green! Can you modify this for repl by the way?

babel/.circleci/config.yml

Lines 12 to 16 in 81158a5

	- &artifact_babel
	path: ~/babel/packages/babel-standalone/babel.js
	- &artifact_babel_min
	path: ~/babel/packages/babel-standalone/babel.min.js

I'm not quite sure how to get repl to support source maps.😕

[JLHwung]

The browser should work out of the box as long as source maps are served. I will give it a try.

[liuxingbaoyu]

Now that the source map is working, maybe you need to enable this in your browser.💐
https://umaar.com/dev-tips/96-resolve-variable-names/

Also interesting is that the previous failure was wrong with NODE_ENV, I think I might open a PR in the future to unify this to BABEL_ENV.

[JLHwung]

@liuxingbaoyu Thanks for the update. I don't find "Resolve variable names" in my devtools settings because it has been enabled by default. There are a new flag "Resolve variable names in expressions" though. See also https://bugs.chromium.org/p/chromium/issues/detail?id=327092

[liuxingbaoyu]

Oh, you're right, I actually enabled this as well.
Since my devtools is in Chinese, I didn't find what the article said, so I finally found it by searching for var in the experimental feature.😄