Instead of rewriting the source, what about creating a sourcemap?

[brianjenkins94]

No description provided.

[jehna]

A great idea! Do you know anything about creating sourcemaps with Babel or similar tools? I think usually Babel creates sourcemaps that start from the original file and you end up with a sourcemap mapping from the end result (e.g. a minified file) to the original file.

In Humanify's case we'd need to do the reverse: Start with a minified file, apply Prettier, Webcrack and Babel transformations, and end up with a source map mapping from the original (minified) file to the end result (un-minified file).

If anybody has ideas on how to do this with any existing tools, I'd be happy to give it a look

[j4k0xb]

Instead of rewriting the source, what about creating a sourcemap?

Renaming itself has many edge cases (const { a } = b -> const { a: foo } = b), and there are also other transformations in humanify.
It would be simpler to rewrite the source and make babel generate a source-map additionally.

Here's a snippet to reverse it: https://gist.github.com/j4k0xb/0d76d103db9696b515ce9c51c45b76b8

• prettier: doesn't support source-maps Source maps prettier/prettier#11136
• webcrack: also not, but it's possible to expose it
• your babel transformations: also possible

and you probably need a way to combine multiple source-maps

[0xdevalias]

It would be simpler to rewrite the source and make babel generate a source-map additionally.

^Big agree on this.

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• prettier: doesn't support source-maps Source maps prettier/prettier#11136

I haven't looked deeply into this, but I switched from prettier to biome in my RE project; I wonder if it can generate sourcemaps for it's formatting? (ChatGPT seems to think it can't)

• https://biomejs.dev/formatter/

Even if neither of these tools can; I wonder if it would be possible to take the 'before formatting' and 'after formatting' code, and then generate a sourcemap based on the diff between them?

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See also:

• Generate 'reverse sourcemap' from unminified output, that can be used directly with the original minified bundle pionxzh/wakaru#66

[pionxzh]

It will be challenging to compare before and after to generate the sourcemap. I didn't look into humanity's source code detailly, but you should be able to let babel generate the sourcemap since most of the operation is renaming. Prettier does not support sourcemap, but I have no idea what other alternatives provide this functionality.

[pionxzh]

I have tried using https://github.com/Rich-Harris/magic-string to do some code transformation with source map support, but I'm not sure if it fits into the use case here.