Graaljs: [Feature Request] Implement `import.meta`

[pmlopes]

See: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/import.meta

The import.meta object is a meta-property exposing context-specific meta data to a JavaScript module. It contains information about the module, like the module's URL.

The motivation can be read on TC39 stage 3 page: https://github.com/tc39/proposal-import-meta/#importmeta

This is already a living standard on a vast majority of engines and is useful to implement script loaders, that require relative paths. When using modules .mjs or the content-type application/javascript+module the information should be already available to graaljs, so it should be a matter of exposing it... (the devil is on the details... ;-)

[wirthi]

Hi Paulo,

we do support import.meta, but we might not yet have all the right properties (e.g. URL that you mentioned).

As it is a stage 3 proposal, we only have it in ECMAScript 2020 mode, i.e. you need to set --js.ecmascript-version=2020.

Best,
Christian

[pmlopes]

@wirthi just be clear, my issue is not related to the node binary, I'm looking into using it from the embedded script side.

[wirthi]

Hi Paulo,

Also for embeddings, we currently support ES2019 by default. Newer features might be available if you set option("js.ecmascript-version", "2020") on the Context.

Best,
Christian

[pmlopes]

Yes I was aware of it. I commented because the issue got labeled "nodejs" .

[wirthi]

Ah, got it, that is incorrect of course.

[wirthi]

I assume the issue is resolved when you set the flag as specified above. Please comment & reopen if this is not the case, thanks!

[pmlopes]

@wirthi on 19.0.0, the meta object is present but the url isn't present,

final Context context = Context.newBuilder("js")
 .builder.option("js.ecmascript-version", "2020")
 .build();

context.eval(
  Source
      .newBuilder("js", "import { f } from './mjs/meta.mjs';\n f();", "myscript.mjs")
      .mimeType(""application/javascript+module")
      .buildLiteral());

And the mjs/meta.mjs file looks like:

console.log(typeof import.meta.url);

export function f () {
  console.log(import.meta.url);
}

And it prints:

undefined

Where I'd expect:

./mjs/meta.mjs

[iamstolis]

the meta object is present but the url isn't present,

FYI: We set url property of import.meta by now, see https://github.com/graalvm/graaljs/commit/65f28d2f20afeec545f19075a89db5fd7c0ccfe0.