Mustache

You need to install the mustache package:

npm i -D mustache

For example, there is the template src/views/page/index.mustache

<html>
  <body>
    <h1>{{ headline }}</h1>
    <ul class="people">
      {{#people}}
      <li>{{.}}</li>
      {{/people}}
    </ul>
  </body>
</html>

Define the preprocessor as a render function:

const HtmlBundlerPlugin = require('html-bundler-webpack-plugin');
const Mustache = require('mustache');

module.exports = {
  plugins: [
    new HtmlBundlerPlugin({
      test: /\.(html|mustache)$/, // add the test option to match *.mustache files in entry
      index: {
        import: './src/views/page/index.mustache',
        data: {
          headline: 'Breaking Bad',
          people: ['Walter White', 'Jesse Pinkman'],
        },
      },
      // define preprocessor as the function that should return a string or promise
      preprocessor: (content, { data }) => Mustache.render(content, data),
    }),
  ],
};