Untitled

<!DOCTYPE html>
<html>
  <body>
    <sample></sample>
    <script type="riot/tag" src="sample.tag"></script>
    <script src="https://cdn.jsdelivr.net/npm/riot@3.8/riot+compiler.min.js"></script>
    <script>
      riot.mount('sample')
    </script>
  </body>
</html>

<sample>
  <h3>▼for-inを使う方法</h3>
  <div each={item in list}>
    <div id='message'></div>
    this.message.innerHTML = {item.content}
  </div>

  <hr>

  <h3>▼直接keyを使う方法</h3>
  <div each={list}>
    <div id='message'></div>
    this.message.innerHTML = {content}
  </div>

  <script>
    this.list = [
      {content:'<p>テキスト111</p>'},
      {content:'<p>テキスト2222</p>'}         
    ]
  </script>
</sample>