Import Attributes

[xtuc]

Request for Mozilla Position on an Emerging Web Specification

• Specification Title: Import attributes
• Specification or proposal URL: https://github.com/tc39/proposal-import-attributes
• Caniuse.com URL (optional):
• Bugzilla URL (optional):
• Mozillians who can provide input (optional):

Other information

Currently Stage 2.

[dbaron]

cc @codehag @annevk @jorendorff @tschneidereit @linclark

[hober]

Note that this feature (or something like it) is necessary to move forward on HTML/CSS/JSON modules.

[tschneidereit]

Also CC @lukewagner. Does it make sense to think about how this interacts with Wasm module linking?

[xtuc]

The proposal has a WebAssembly section. It wouldn't be in TC39 but our plan is to allow to express the same attributes than in JavaScript. The Wasm producer will need some syntax, or can based on the file extension.

[lukewagner]

The use of a custom section to allow wasm modules imported via ESM-integration to import non-wasm/JS modules seems like a reasonable approach. Other than that, there's not any interaction I can think of with wasm module linking until "evaluator attributes" are added (which it sounds like is explicitly postponed). So 👍 from a wasm pov.

[codehag]

I discussed this with @annevk some time ago - it's worth pursuing with a few caveats. However, those have been met before stage 2 (we considered inbound syntax as important, as otherwise it might not be used). I don't think our support has changed since. 👍

[littledan]

@lukewagner Do you think "evaluator attributes" would be useful for expressing permissions/capabilities for Wasm modules?

[annevk]

@xtuc note that Wasm should not use the file externsion on the web as that would be counter to how the web works.

[lukewagner]

@littledan I think so: evaluator attributes would allow JS code to pass the import values used to instantiate a wasm module (either to limit capabilities or to allow explicit parameterization) while still getting to use the ESM module loader system. To do so without evaluator attributes, you need to resort to using the imperative JS API and manual fetch()ing.

[dbaron]

So does it make sense to mark this as worth prototyping, or are there things that should happen before we're willing to do that?

[codehag]

I think we can mark it as worth prototyping