Custom Asciidoctor.js html converter with Nunjucks templates

Many thanks to Github user @Mogztter for showing me this code and pointing me the right direction.

I needed to add a custom templating system to the stasis-reactor project and was having some difficulty with the current tech stack I have chosen. After a brief and enlightening post from @Mogztter, I was quickly able to put together a branch for adding this functionality.

This code will use the Asciidoctor.js project to load an Asciidoc formatted file and then convert that file into HTML using the Nunjucks template language as a final conversion engine.

This code will convert the Asciidoc at the Document entity level and pass that to the Nunjucks converter. It passes the document object to the Nunjucks template as a variable named context.

const asciidoctor = require("asciidoctor.js")();
const nunjucks = require("nunjucks");

nunjucks.configure({autoescape: false});


const template = `<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8">
    <title>{{ context.getDoctitle() }}</title>
  </head>
  <body>
    <h1>{{ context.getDoctitle() }}</h1>
    {{ context.getContent() }}
  </body>
</html>`;


class TemplateConverter {
  constructor () {
    this.baseConverter = asciidoctor.Html5Converter.$new();
    this.templates = {
      document: (node) => nunjucks.renderString(template, {context: node})
    };
  }

  convert (node, transform, opts) {
    const template = this.templates[transform || node.node_name];
    if (template) {
      return template(node);
    }
    return this.baseConverter.convert(node, transform, opts);
  }
}

asciidoctor.ConverterFactory.register(new TemplateConverter(), ["html5"]);
var adoc = asciidoctor.convertFile("./example1.adoc");

With this as the starting point I was quickly able to add a little more sugar to allow the Nunjucks template to be stored in an external file. This now opens up an easy avenue for stasis-reactor users to customize their document output.