renderFeed.js

let feed = {
  type: 'rss',
  props: {
    'xmlns:blogChannel': 'https://...',
    version: '2.0',
    children: [
      {
        type: 'channel',
        props: {
          title: 'Remix Blog',
          link: 'https://blog.remix.run',
          description: '...',
          language: 'en-us',
          copyright: '...',
          children: [
            {
              type: 'item',
              props: {
                description: '...',
                pubDate: '...',
                guid: '...',
                dangerouslySetInnerHTML: '<a href="...">click me</a>'
              }
            }
          ]
        }
      }
    ]
  }
};

function escapeHtml(unsafe) {
  return unsafe
    .replace(/&/g, '&amp;')
    .replace(/</g, '&lt;')
    .replace(/>/g, '&gt;')
    .replace(/"/g, '&quot;')
    .replace(/'/g, '&#039;');
}

function stringifyAttributes(attrs) {
  return Object.keys(attrs)
    .map(key => `${key}="${escapeHtml(attrs[key])}"`)
    .join(' ');
}

function createMarkup({ type, props }) {
  let markup = `<${type}`;

  let { children, dangerouslySetInnerHTML, ...rest } = props;
  if (Object.keys(rest).length > 0) {
    markup += ` ${stringifyAttributes(rest)}`;
  }

  if (dangerouslySetInnerHTML) {
    markup += '>' + dangerouslySetInnerHTML + `</${type}>`;
  } else if (children) {
    let innerMarkup = children.map(createMarkup);
    if (innerMarkup === '') {
      markup += ` />`;
    } else {
      markup += `>` + innerMarkup + `</${type}>`;
    }
  } else {
    markup += ` />`;
  }

  return markup;
}

console.log(createMarkup(feed));