[Feature] ESM support

[estacioneto]

Hello!

Kulala works amazingly for my needs but some devs on our team work with httpYac on VSCode. One big difference is that this works fine on kulala:

async function main() {
  request.variables.set('computed_request_body', await heavyComputationOrFetch())
}

main()

...while on httpYac we would need a top-level await, meaning:

async function main() {
  request.variables.set('computed_request_body', await heavyComputationOrFetch())
}

await main()

Node.js already supports top-level awaits, but AFAIK they are available only for ES Modules (.mjs), while I believe Kulala creates a CommonJS (.js) file for running the script.

Possible solution

• Allow .mjs scripts, which can be identified by their file extension
  • This could also mean supporting the import syntax (currently not supported by httpYac, but flagged, but supported by intellij), since simply changing the generated script as mjs throws ReferenceError: require is not defined in ES module scope, you can use import instead.

Additional info

Here's a related issue for plugin compatibility, but I believe that supporting ESM here would be a win even if the import is not supported by httpYac.

[YaroSpace]

I am all for any improvements to Kulala.

However, as I mentioned, js/ts is really not my domain, so unfortunately I only vaguely understand what needs to be done here and I would need to research on this topic.

It would be great if you could contribute yourself, especially since you understand this much better both in terms of implementation and of an end user. Or, if you do not have the time, it would be helpful if you could provide some more detailed guidance.

[estacioneto]

Sure. I'll take a look whenever I can and try to contribute myself. Thanks for the acceptance!

[gorillamoe]

Idk from the top of my head, if this is easy to implement, because we're basically creating temporary files for each script you have in your requests 🙈. So let's say, you have just a console.log(true) either just inline or as a separate file (doesn't matter because we're just reading the whole file contents or taking the inline string) -> we will basically concatenate our basic "framework" (which includes functions defined by the "standard"; which is basically mostly the intellij guys), so that your script has access to these functions during runtime and then append your script. The we basically just run this through node.

Because the output is indeed cjs, I have to check how to allow both cjs/js and mjs.

But I think that's a good addition, thanks for coming up with this.

[estacioneto]

@gorillamoe agree. It's not that easy, but it's definitely possible and it would be cool to have at least a small working version of it.

I achieved it very rudimentarily here by using rollup to bundle the external files, which would allow for having imports working out of the box, and also creating (pre|post)-(request|response).mjs files to be added to the beginning of the file.

I haven't tested it thoroughly and it would be amazing to have some feedback from you folks before continuing (a hand for crafting the test cases would also be amazing). In a nutshell, this is how I see it being implemented.