HTMLElement: showPopover() メソッド

showPopover()

<div id="mypopover" popover>
  <h2>Help!</h2>
  <p>You can use the following commands to control the app</p>
  <ul>
    <li>Press <ins>C</ins> to order cheese</li>
    <li>Press <ins>T</ins> to order tofu</li>
    <li>Press <ins>B</ins> to order bacon</li>
    <hr />
    <li>Say "Service" to summon the robot waiter to take your order</li>
    <li>Say "Escape" to engage the ejector seat</li>
  </ul>
</div>

const popover = document.getElementById("mypopover");
document.addEventListener("keydown", (event) => {
  if (event.key === "h") {
    popover.showPopover();
  }
});