By implementing a html renderer in Zig, we removed the dependency on md4c-html.c and some libc functions. The compiled wasm binary is now 50% smaller (from 98KB to 52KB).

Since we are now using a custom html renderer, we can also add some features that are not supported by md4c-html.c, such as:

• Add anchor to the headers

  '# Hello World!' -> <h1>Hello World! <a class="anchor" id="hello-world" href="#hello-world"></h1>
  

• Sync the buffer between the host and the wasm module that introduces a streaming API for large markdown files or a http server to stream the response.

  import { mdToReadableHtml } from "md4w";
  
  const largeMarkdown = `# Hello, World!\n`.repeat(1_000_000);
  const readable = mdToReadableHtml(largeMarkdown);
  
  // write to file
  const file = await Deno.open("/foo/bar.html", { write: true, create: true });
  readable.pipeTo(file.writable);
  
  // or send to client
  const response = new Response(readable, {
    headers: { "Content-Type": "text/html" },
  });
  

• And we can now send the code blocks to the host to highlight it. You can call the setCodeHighlighter function to add any code highlighter you like.

  import { setCodeHighlighter } from "md4w";
  
  setCodeHighlighter((code, lang) => {
    return `<pre><code class="language-js"><span style="color:#green">...<span></code></pre>`;
  });