Add a JSONC language variant for "JSON with Comments"

[michaelblyons]

Similar to #406, which correctly points out that comments are not permitted in the JSON spec, can a new, very similar language be added that does permit comments and trailing commas?

This is often used in configuration files for (among other things) VS Code and Sublime Text. Github comparison of codefences for json versus jsonc:

[
    // The foo
    { "foo": [ "baz", 4, true ] },
    // The bar
    { "bar": [ "biff", 10, false ] },
]

[
    // The foo
    { "foo": [ "baz", 4, true ] },
    // The bar
    { "bar": [ "biff", 10, false ] },
]

Right now, I use javascript for these like #406 suggests, but it is much easier to discriminate keys and values with the JSON highlighting.

[joshgoebel]

Would this have to be a variant. What if we just added comments to the JSON parser so it simply allowed comments if they were present?

[michaelblyons]

@yyyc514 Personally, I wouldn't mind if they were permitted in the JSON parser, but a repo member already weighed in on that in #406. I hoped that a variant would be a reasonable compromise.

[joshgoebel]

Good catch. I just responded to that comment, we'll see where it goes. :-)

[glen-84]

@yyyc514 Why don't you want to use jsonc, like GitHub does?

[joshgoebel]

Why don't you want to use jsonc, like GitHub does?

I have no idea what this question even means. Did GitHub already write a Highlight.js syntax we can just "use", otherwise I'm not sure what you're asking by "use".

We're talking about the simplest/easiest to maintain/most pragmatic way to add comment highlighting to Highlight.js. Personally I think the answer is like "add it to the json syntax and make jsonc an alias". Aliases is a built in concept of Highlight.js for situations like this.

[joshgoebel]

Here is my attempt:

https://github.com/highlightjs/highlight.js/pull/2155/files

Welcome for thoughts/critiques.

[glen-84]

I have no idea what this question even means

I was asking why you didn't want to use a distinct name like jsonc (used on GitHub), to differentiate between JSON and JSON with comments.

Inexperienced developers may be led to believe that JSON supports comments, which it obviously doesn't.

Neither GitHub nor GitLab highlight comments when using the json language (which is the correct behaviour, in my opinion).

[joshgoebel]

I was asking why you didn't want to use a distinct name like jsonc (used on GitHub), to differentiate between JSON and JSON with comments.

Oh I don't really have an opinion on that. I'm not sure "jsonc" is an official thing though. You'll see I asked in the other thread if we should make an alias for "jsonc" or not.

Inexperienced developers may be led to believe that JSON supports comments, which it obviously doesn't.

That would be equally possible if we had two different ones and "auto-detected" the one they were using... same issue, so I don't think this is a huge problem.

[glen-84]

I'm not sure "jsonc" is an official thing though

It's not really an "official format" or anything, just a way of separating the two variations. FWIW, VS Code also uses it.

[egor-rogov]

I was asking why you didn't want to use a distinct name like jsonc (used on GitHub), to differentiate between JSON and JSON with comments.

Inexperienced developers may be led to believe that JSON supports comments, which it obviously doesn't.

Well, highlighter doesn't have to be as rigorous as compilers are. For now, fixed via #2155.
We can add an alias jsonc though, if it helps.

[joshgoebel]

@glen-84 Would you be happier if we added a "jsonc" alias?

[glen-84]

@yyyc514 It would be nice to have that as an option. 🙂