Support remark syntax plugins in @mdx-js/language-server

[remcohaszing]

Initial checklist

• I read the support docs
• I read the contributing guide
• I agree to follow the code of conduct
• I searched issues and couldn’t find anything (or linked relevant results below)

Problem

The language service was written with support for remark/micromark syntax plugins in mind, but not the language server. We need to think of a way for users to define which remark plugins to use.

Solution

The language server uses TypeScript, which loads tsconfig.json. We could extend tsconfig.json with an mdx property. For example ts-node does this too.

We can then use load-plugin to load the plugins.

{
  "compilerOptions": {
    "module": "node16",
    "strict": true,
    // etc…
  },
  "mdx": {
    "plugins": [
      "remark-frontmatter",
      "remark-gfm"
    ]
  }
}

Alternatives

We could also use LSP workspace configuration.

Alternatively we could investigate a more common MDX configuration file and look into creating an MDX CLI. I.e. remark-cli doesn’t support MDX out of the box. (unifiedjs/unified-engine#56)