@11ty/eleventy-plugin-rss/src/htmlToAbsoluteUrls.js

Generate an Atom, RSS, or JSON feed with Eleventy.

const posthtml = require('posthtml');
const urls = require('@11ty/posthtml-urls')
const absoluteUrl = require("./absoluteUrl");

// This is deprecated! Use the Eleventy HTML <base> plugin instead (2.0+)
module.exports = async function(htmlContent, base, processOptions = {}) {
  if( !base ) {
    throw new Error( "eleventy-plugin-rss: htmlToAbsoluteUrls(absolutePostUrl) was missing the full URL base `absolutePostUrl` argument.")
  }

  let options = {
    eachURL: function(url) {
      return absoluteUrl(url.trim(), base);
    }
  };

  let modifier = posthtml().use(urls(options));

  let result =  await modifier.process(htmlContent, processOptions);
  return result.html;
};