Import Maps

[LeviPesin]

Description

Import maps are really useful and really needed for very many developers. They are supported everywhere except Safari and Firefox.

Rationale

They are extremely useful for JavaScript libraries and their developers, for example three.js.

Specification

https://wicg.github.io/import-maps/

Tests

https://wpt.fyi/results/?label=master&label=experimental&aligned&view=subtest&q=import-maps

[foolip]

It looks like the spec here isn't on the W3C Recommendation Track. @domenic, as the editor of the spec, what's the likely destination of this once it leaves incubation, and when might that happen?

[domenic]

Ah, right, that's what I forgot to do today---add a redirect! https://html.spec.whatwg.org/#import-maps

[foolip]

Excellent, thanks @domenic!

[annevk]

One potential problem here is that WebKit supports a superset: whatwg/html#8355. It would be undesirable if supporting external import maps would give you a lower score.

(Also note that with 3 engines "everywhere except 2" leaves 1. 😊)

[foolip]

This was mentioned by WordPress developer @youknowriad in https://make.wordpress.org/core/2022/10/10/seeking-proposals-for-interop-2023/#comment-43928:

import maps: Would love support without polyfills as this would allows us to improve the way scripts are registered/handled in WP and introduce lazy loaded scripts…

Thanks Riad for sharing!

[gsnedders]

We probably want to exclude /import-maps/acquiring/modulepreload.html and /import-maps/acquiring/modulepreload-link-header.html.

[tbondwilkinson]

Import maps are a P4 for Google's closure library

"It's possible this could help with polyfills, maybe?"

[LeviPesin]

There is a es-module-shims polyfill.

[gsnedders]

Note /import-maps/data-driven/ are currently failing in WebKit for unrelated reasons (related to when load events are fired on iframe elements).

I don't know how difficult this would be to workaround (it might be as simple as passing {once: true} to event listener), but we probably ought not test totally unrelated behaviour here.

[foolip]

In the MDN short survey on APIs & JavaScript, "Import Maps" was selected by ~13% of survey takers, putting it in the bottom third of options. (There is some uncertainty as with any survey data.)

[foolip]

Thank you for proposing Import Maps for inclusion in Interop 2023.

We are pleased to let you know that this proposal was accepted as part of the Modules focus area. You can follow the progress of this Focus Area on the Interop 2023 dashboard.

For an overview of our process, see the proposal selection summary. Thank you for contributing to Interop 2023!

Posted on behalf of the Interop team.