Regression in compatibility with Tailwindcss

[Nautigsam]

In version 2.0.6 I can run tailwind as such:

deno run -A npm:tailwindcss

After upgrading to 2.1.1 the same command fails:

error: Uncaught (in promise) ReferenceError: module is not defined                                                                                                         
module.exports = {                                                                   
^                                         
    at file:///home/project/tailwind.config.js:2:1
    at loadESMFromCJS (node:module:777:21)                                           
    at Module._compile (node:module:722:12)
    at loadMaybeCjs (node:module:770:10)                                                                                                                                   
    at Object.Module._extensions..js (node:module:755:12)                                                                                                                  
    at Module.load (node:module:662:32)                                              
    at Function.Module._load (node:module:534:12)                    
    at Module.require (node:module:681:19)                                           
    at require (node:module:812:16)       
    at file:///home/project/.cache/deno/npm/registry.npmjs.org/tailwindcss/3.4.1/lib/lib/load-config.js:46:27
                                                                                     
    info: Deno supports CommonJS modules in .cjs files, or when the closest
          package.json has a "type": "commonjs" option.           
    hint: Rewrite this module to ESM,                                                
          or change the file extension to .cjs,
          or add package.json next to the file with "type": "commonjs" option.                                                                                             
    docs: https://docs.deno.com/go/commonjs

[dsherret]

I'm not able to reproduce this. Running deno run -A --reload npm:[email protected] runs successfully for me.

[Nautigsam]

It works without arguments indeed, my bad. I did not include the arguments -i and -o in my report.

The full command I run is the following:

deno run -A --reload npm:[email protected] -i tailwind.css -o out.css

[dsherret]

That also works.

@nathanwhit pointed out he can reproduce this when he has a tailwind.config.js with a module.exports = ... and that makes sense based on the error message.

So it's loading the tailwind.config.js, but that's defined as being ESM. There was a bug fix in Deno where we would incorrectly and accidentally identify the module kind (esm or cjs) based on the referrer (this is really bad to do for a lot of reasons I won't get into here). This file is probably defined in a spot that is considered ESM. You can fix this by changing module.exports = { to export default { in tailwind.config.js or if you have a package.json, you can tell Deno to treat .js files as possibly cjs in your Deno project by adding { "type": "commonjs" } to it.

[dsherret]

Also, sorry this bug fix caused a new error to appear, but Deno's behaviour is more correct now and will lead to less bugs/errors overall.

[Nautigsam]

I confirm changing the config file to ESM works. Thank you!

[dsherret]

Note I've opened #27094 which would tell Deno to attempt to load files as CJS even when there's not a "type": "commonjs" in the package.json (or even when there's not a package.json at all). This is opt-in because it makes module loading do more work and it could potentially break some applications.