shiki-twoslash

shiki-twoslash

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

Provides the API primitives to mix shiki with @typescript/twoslash to provide rich contextual code samples.

Things it handles:

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

Libraries for common tools which use this generator:

• gatsby-remark-shiki-twoslash - For instantly using with Gatsby
• remark-shiki-twoslash - Any JS static site generator using Remark (11ty, nextjs, )

Or you can use the API directly in a Node.js script:

import { renderCodeToHTML, runTwoSlash, createShikiHighlighter } from "shiki-twoslash"
import { writeFileSync } from "fs"

const go = async () => {
  const highlighter = await createShikiHighlighter({ theme: "dark-plus" })
  const code = `
// Hello world
const a = "123"
const b = "345"
    `
  const twoslash = runTwoSlash(code, "ts", {})
  const html = renderCodeToHTML(twoslash.code, "ts", ["twoslash"], {}, highlighter, twoslash)

  fs.writeFileSync("output.html", html, "utf8")
}

User Settings

The config which a user passes is an intersection of Shiki's HighlighterOptions

interface HighlighterOptions {
  theme?: IThemeRegistration
  langs?: (Lang | ILanguageRegistration)[]
  themes?: IThemeRegistration[]
  /**
   * Paths for loading themes and langs. Relative to the package's root.
   */
  paths?: IHighlighterPaths
}

With twoslash's TwoSlashOptions

export interface TwoSlashOptions {
  /** Allows setting any of the handbook options from outside the function, useful if you don't want LSP identifiers */
  defaultOptions?: Partial<ExampleOptions>
  /** Allows setting any of the compiler options from outside the function */
  defaultCompilerOptions?: CompilerOptions
  /** Allows applying custom transformers to the emit result, only useful with the showEmit output */
  customTransformers?: CustomTransformers
  /** An optional copy of the TypeScript import, if missing it will be require'd. */
  tsModule?: TS
  /** An optional copy of the lz-string import, if missing it will be require'd. */
  lzstringModule?: LZ
  /**
   * An optional Map object which is passed into @typescript/vfs - if you are using twoslash on the
   * web then you'll need this to set up your lib *.d.ts files. If missing, it will use your fs.
   */
  fsMap?: Map<string, string>
  /** The cwd for the folder which the virtual fs should be overlaid on top of when using local fs, opts to process.cwd() if not present */
  vfsRoot?: string
}

Most people will want to set a theme, and maybe vfsRoot if they want to do twoslash with custom libraries in a monorepo:

{
  resolve: "gatsby-remark-shiki-twoslash",
  options: {
    theme: "github-light",
    vfsRoot: path.join(__dirname, "..", "..")
  },
}

Common Use Case

Node Types in a Code Sample

To get the Node globals set up, import them via an inline triple-slash reference:

```ts twoslash
/// <reference types="node" />
import { execSync } from "child_process"
const files = execSync("git status --porcelain", { encoding: "utf8" })
files.length
```

This applies to other projects which use globals, like Jest etc. If you think that's ugly, that's OK, you can use // ---cut--- to trim the user-visible output.

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) {
  const highlighter = await createShikiHighlighter(userOpts)
  visit(markdownAST, "code", visitor(highlighter, userOpts))
}

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
• remark-shiki-twoslash