feat: add mdx support

[I-3B]

closes #211

This line may causes problem if some users where only using doctoc for .md files, I didn't check for it, should I?

[I-3B]

@AndrewSouthpaw would you please review this?

[chris-dura]

This line may causes problem if some users where only using doctoc for .md files, I didn't check for it, should I?

So, if I understand, this means that users would all of a sudden start getting TOCs in their .mdx files, which they weren't before... I could see how this would be considered a "breaking change" at worst, and annoying at best to users 😅.

I don't think it's worth forcing a MAJOR version bump, so to keep it backwards compatible, you may want to make the MDX support "opt-in", so the doctoc command does the same thing by default, and you have to explicitly enable mdx support?

[I-3B]

This line may causes problem if some users where only using doctoc for .md files, I didn't check for it, should I?

So, if I understand, this means that users would all of a sudden start getting TOCs in their .mdx files, which they weren't before... I could see how this would be considered a "breaking change" at worst, and annoying at best to users 😅.

I don't think it's worth forcing a MAJOR version bump, so to keep it backwards compatible, you may want to make the MDX support "opt-in", so the doctoc command does the same thing by default, and you have to explicitly enable mdx support?

I can think of two approaches:

• .mdx is only matched if --syntax mdx is provided, but would also still match .md
• the more expected behavior, only match .mdx if --syntax mdx and only match .md and .markdown if --syntax md (default)

[chris-dura]

I like what you're doing with a --syntax argument better... but I'm an idiot and must've forgot to open a PR from my fork where I implemented this for a local project, just for reference:

https://github.com/thlorenz/doctoc/pull/241

Anyway, not something I thought about in mine, but, I would allow --syntax to support just .md/.markdown (default), just .mdx, or "all syntaxes". Then, the default behavior is unchanged, but you can opt-in to doing .mdx files, or all of them?

[AndrewSouthpaw]

That seems reasonable to me. Not breaking the default behavior is important.

[I-3B]

@AndrewSouthpaw hi!

fixed the issue mentioned before here a6ee89ccf7c5f3e0f2bcba4df67bd473979a8b7f, so now mdx files won't get matched unless --syntax mdx is explicitly specified.

[AndrewSouthpaw]

Hi there! Sorry it took so long to get back to you. The code looks good, all it needs now is some test coverage and we can ship it! 🥳

[I-3B]

Hi~ @AndrewSouthpaw added some tests, should cover the new change, would you like me to add more?

[I-3B]

Hi @AndrewSouthpaw ! thanks for the thorough review, can you please go through the new commits to check if they cover the review?

[AndrewSouthpaw]

Perfect! One quick lint cleanup and this is good to go. Thanks @I-3B.