shiki-twoslash

shiki-twoslash

Documentation / made lovely by counting words / maybe we would read!

Provides the API primitives to mix shiki with @typescript/twoslash.

Things it handles:

• Shiki bootstrapping: createShikiHighlighter
• Running Twoslash over code, with caching and DTS lookups: runTwoSlash
• Rendering any code sample with Shiki: renderCodeToHTML

Useful, but not critical:

• Checking if shiki can handle a code sample: canHighlightLang

API

The user-exposed parts of the API is a single file, you might find it easier to just read that: src/index.ts.

createShikiHighlighter

Sets up the highlighter for Shiki, accepts shiki options:

async function visitor(highlighterOpts, shikiOpts) {
  const highlighter = await createShikiHighlighter(highlighterOpts)
  visit(markdownAST, "code", visitor(highlighter, shikiOpts))
}

renderCodeToHTML

/**
 * Renders a code sample to HTML, automatically taking into account:
 *
 *  - rendering overrides for twoslash and tsconfig
 *  - whether the language exists in shiki
 *
 * @param code the source code to render
 * @param lang the language to use in highlighting
 * @param info additional metadata which lives after the codefence lang (e.g. ["twoslash"])
 * @param highlighter optional, but you should use it, highlighter
 * @param twoslash optional, but required when info contains 'twoslash' as a string
 */
export declare const renderCodeToHTML: (
  code: string,
  lang: string,
  info: string[],
  shikiOptions?: import("shiki/dist/renderer").HtmlRendererOptions | undefined,
  highlighter?: Highlighter | undefined,
  twoslash?: TwoSlashReturn | undefined
) => string

For example:

const results = renderCodeToHTML(node.value, lang, node.meta || [], {}, highlighter, node.twoslash)
node.type = "html"
node.value = results
node.children = []

Uses:

• renderers.plainTextRenderer for language which shiki cannot handle
• renderers.defaultRenderer for shiki highlighted code samples
• renderers.twoslashRenderer for twoslash powered TypeScript code samples
• renderers.tsconfigJSONRenderer for extra annotations to JSON which is known to be a TSConfig file

These will be used automatically for you, depending on whether the language is available or what the info param is set to.

To get access to the twoslash renderer, you'll need to pass in the results of a twoslash run to renderCodeToHTML:

const highlighter = await createShikiHighlighter(highlighterOpts)
const twoslashResults = runTwoSlash(code, lang)
const results = renderCodeToHTML(
  twoslashResults.code,
  twoslashResults.lang,
  node.meta || ["twoslash"],
  {},
  highlighter,
  node.twoslash
)

runTwoSlash

Used to run Twoslash on a code sample. In this case it's looking at a code AST node and switching out the HTML with the twoslash results:

if (node.meta && node.meta.includes("twoslash")) {
  const results = runTwoSlash(node.value, node.lang, settings)
  node.value = results.code
  node.lang = results.extension
  node.twoslash = results
}

Used in:

• gatsby-remark-shiki-twoslash