HTMLElement: translate プロパティ

<div>
  <span>The content may always be translated: </span>
  <span translate="yes">El contenido será traducido</div>
</div>
<div>
  <span id="translate-label">The content may be translated:</span>
  <span id="translate-element" translate="no">El contenido puede ser traducido.</div>
</div>
<input id="translate-controller" type="checkbox" /> Enable translation

const label = document.getElementById("translate-label");
const element = document.getElementById("translate-element");
const controller = document.getElementById("translate-controller");
controller.addEventListener("change", (e) => {
  if (controller.checked) {
    element.translate = true;
    label.innerText = "The content may be translated:";
  } else {
    element.translate = false;
    label.innerText = "The content may not be translated:";
  }
});