Consider supporting importing files as jsonc / json5

[lucacasonato]

import data from "./data.jsonc" with { type: "jsonc" };
import data from "./data.json5" with { type: "json5" };

I'm not to sure about this myself yet, but it may be interesting. What are peoples' thoughts?

[lino-levan]

Although it may seem like a practical inclusion, I worry that it's straying away from web spec. How would we decide which formats to allow? Would tomls be importable? How about yaml? I don't see a clear way we can draw the line here. I'm open to hearing what you think, I'm just a little skeptical about Deno straying away from spec text.

[Jabolol]

Even though I agree with @lino-levan, since Deno supports deno.jsonc configuration files implementing this would make sense. There are times when one wants to store extra configuration in the deno.jsonc file to reference it in the project programmatically, and this would help.

[lino-levan]

Outside of static analysis, this doesn't provide a lot of benefit imo. Are there enough people asking for jsonc specifically? I'd love to get a sense of if people actually want this.

[scarf005]

i'd like to share my use-use:

• import fmt property of deno.jsonc
• feed it as an option to wasm dprint formatter
• use it for formatting texts programmatically

it's more of an workaround, however once deno exposes fmt as an runtime API (#10731).

[lino-levan]

Perhaps #19322 would be a less hacky way of doing it while not exposing a runtime API?

[pubmikeb]

JSON is a great (de-)serialization format for apps' configs and data.
However, it doesn't support comments. Luckly, there are two formats, which support comments in JSON: .jsonc and .json5.

As a modern application environment, it would be great to be able to use .jsonc and .json5 instead of classical .json in projects.

Following #20833, please add support importing files as .jsonc.

[Malix-Labs]

Also note that JSON5 is arguably a better spec than JSONC, see microsoft/vscode#100688

[SebastienGllmt]

I think { type: "jsonc" } makes sense because deno.json files are actually valid jsonc files (and this isn't planned to change per #20681)

That means that doing import DenoConfig from "../deno.json" with { type: "json" }; actually may fail because the file might be jsonc under the hood. This is counter-intuitive because even the Deno compiler complains, telling you that you can only import json files with type: "json" even though that fails

Note that if you don't want to use fs, you could use type: "text" which is planned (see here and here) (but not implemented yet), but

1. It's a bit unintuitive to see from "../deno.json" with { type: "text" };
2. We would have to remove the compiler error telling you that you must use type: "json" when importing .json files because it would actually be the wrong import attribute when dealing with jsonc files like deno.json.

Cascading implications

You could argue the compiler strictness around { type: "json" } would have to be loosened anyway because many other projects allow json5 content in .json files (so you would at least have to support { type: "json" }, { type: "json5" }, { type: "jsonc" } at which point maybe just allowing { type: "text" } doesn't sound so bad

Some people have even suggested allowing to remove the import assertion entirely with a flag like #26157

[scarf005]

How about just allowing importing JSONc as JSON with its comments stripped away?

import data from "./data.jsonc" with { type: "json" }

related: https://douglascrockfordisnotyourdad.technomancy.us

[SebastienGllmt]

How about just allowing importing JSONc as JSON with its comments stripped away?

Be careful because the behavior of { type: "json" } is explicitly mentioned in the import attributes specification because it's also used by web browsers

If you wanted to go this option, Deno would need to generate extra code when transpiling to vanilla JS for browsers when it seems { type: "json" } to make it work, and so it depends if the Deno team team wants to take that approach.

It also doesn't solve the problem that some projects use json5 for their .json files instead of jsonc, so now you'd have to ship a json5 parser in every webpage built with Deno that imports json files