parcel-bundler/src/transforms/posthtml.js

<p align="center"> <a href="https://parceljs.org/" target="_blank"> <img alt="Parcel" src="https://user-images.githubusercontent.com/19409/31321658-f6aed0f2-ac3d-11e7-8100-1587e676e0ec.png" width="749"> </a> </p>

const loadPlugins = require('../utils/loadPlugins');
const posthtml = require('posthtml');
const Config = require('../utils/config');
const htmlnano = require('htmlnano');

module.exports = async function(asset) {
  let config = await getConfig(asset);
  if (!config) {
    return;
  }

  await asset.parseIfNeeded();
  let res = await posthtml(config.plugins).process(asset.ast, config);

  asset.ast = res.tree;
  asset.isAstDirty = true;
};

async function getConfig(asset) {
  let config =
    asset.package.posthtml ||
    (await Config.load(asset.name, [
      '.posthtmlrc',
      '.posthtmlrc.js',
      'posthtml.config.js'
    ]));
  if (!config && !asset.options.minify) {
    return;
  }

  config = config || {};
  config.plugins = await loadPlugins(config.plugins, asset.name);

  if (asset.options.minify) {
    config.plugins.push(htmlnano());
  }

  config.skipParse = true;
  return config;
}