whatwg/tc39/node.js JSON modules

[dnalborczyk]

consider deprecating the rollup json plugin https://github.com/rollup/rollup-plugin-json and pull in core functionality into rollup main, with some changes in behavior.

the expected change would be to be consistent with (see below) whatwg/tc39/node.js and treat the json import as a default import, and do not allow or support named exports .

couple reasons for not considering named exports: confusing and non-consistent behavior of "JSON Object" vs "JSON Array" (+ others, "string", null etc.). Also how to handle a "default" property on an "JSON Object".

if the separate json plugin is still a better option, it would be still great to adopt the consensus of not allowing named exports to have the same expectations working across browsers, engines and tools.

additional background:

WHATWG
whatwg/html#4315
https://html.spec.whatwg.org/#json-module-script
https://html.spec.whatwg.org/#creating-a-json-module-script (give it some time to load)

TC39 https://docs.google.com/presentation/d/1w8jWjD41htD7VxOejFqiHi6uGgHVWtZ_XmgFxgKkS7Q/edit#slide=id.g5947c7781f_0_20

Node.js modules working group
nodejs/node#27752

related Webpack issue:
webpack/webpack#9246

Expected Behavior / Situation

// allow
import data from './data.json'

// disallow, throw
import { foo } from './data.json'

Actual Behavior / Situation

Modification Proposal

edit: modified reasons section, added webpack issue reference

[shellscape]

@lukastaegert what are your thoughts on this? I don't personally have an issue with JSON module support being external. But it seems everyone and their brother has integrated it into their core.

[lukastaegert]

If it becomes an official feature, we could put it into core. But there will still be need for rollup-plugin-json as property tree-shaking is a useful feature that even Rollup itself relies upon. I would see this as a nice-to-have.

[dnalborczyk]

this proposal was the precursor to import assertions and can be closed.