shiki-rehypedeprecated

Rehype plugin to highlight code blocks with Shiki

Usage no npm install needed!

<script type="module">
  import shikiRehype from 'https://cdn.skypack.dev/shiki-rehype';
</script>

README

Shiki Rehype

Rehype plugin to highlight code blocks with Shiki

Source Package Continuous Integration

Installation

$ npm install shiki-rehype shiki

Format

Code blocks must have the following format:

<pre>
<code class="language-javascript">
return unified();
</code>
</pre>

This is the format produced by remark-parse & remark-rehype from the following Markdown:

```javascript
return unified();
```

Example

$ npm install typescript ts-node unified remark-parse remark-rehype shiki-rehype shiki rehype-stringify

tsconfig.json

{
  "compilerOptions": {
    "target": "ES2019",
    "module": "commonjs",
    "strict": true,
    "esModuleInterop": true
  }
}

example.ts

import unified from "unified";
import remarkParse from "remark-parse";
import remarkRehype from "remark-rehype";
import rehypeShiki from "shiki-rehype";
import * as shiki from "shiki";
import rehypeStringify from "rehype-stringify";

(async () => {
  console.log(
    unified()
      .use(remarkParse)
      .use(remarkRehype)
      .use(rehypeShiki, {
        highlighter: await shiki.getHighlighter({ theme: "light-plus" }),
      })
      .use(rehypeStringify)
      .processSync(
        `
\`\`\`javascript
return unified();
\`\`\`
`
      )
      .toString()
  );
})();
$ npx ts-node example.ts
<pre class="shiki" style="background-color: #FFFFFF"><code><span class="line"><span style="color: #AF00DB">return</span><span style="color: #000000"> </span><span style="color: #795E26">unified</span><span style="color: #000000">();</span></span></code></pre>

Options

  • highlighter (required): An instance of the Shiki highlighter.
  • throwOnUnsupportedLanguage (default: false): A boolean indicating whether to throw an exception if a code block refers to an unsupported language.

Security

Shiki Rehype doesn’t open you up to cross-site scripting (XSS) attacks as long as Shiki doesn’t (which it doesn’t).

How Is This Different from rehype-shiki?

rehype-shiki is great! That’s how I learned about Shiki and I fell in love with it. The following are the ways in which Shiki Rehype is different:

  1. TypeScript support.
  2. Shiki is declared as a peerDependency, so Shiki Rehype doesn’t have to be updated when new versions of Shiki are released (as long as Shiki’s API remain compatible). See https://github.com/rsclarke/rehype-shiki/pull/48 https://github.com/rsclarke/rehype-shiki/pull/46 https://github.com/rsclarke/rehype-shiki/issues/47 https://github.com/rsclarke/rehype-shiki/issues/2.
  3. You must pass in an instance of the Shiki highlighter, Shiki Rehype won’t create one for you. This means that:
    1. The Shiki highlighter instance is reused on every invocation of the processor, instead of being recreated every time you call the processor.
    2. The transformer is synchronous, so you may use it with .processSync().
  4. Instead of looking at the tokens produced by Shiki and generating hast, Shiki Rehype lets Shiki produce HTML and parses the result. The advantage is that when Shiki improves the output with things like italics, then Shiki Rehype will pick the changes up with no extra work. The disadvantage is that we’re producing HTML as a string and then parsing it right back; this is slower, but in most cases it won’t matter and I think the previous advantage outweighs this disadvantage. (Also, the language-* class will be removed from the produced HTML, so you may need to adapt your CSS accordingly.)

That said, I contacted the maintainers of rehype-shiki and try to merge the code bases. We’ll see…