HTMLButtonElement: command property - Web APIs

HTMLButtonElement: command property - Web APIs | MDN

Value

A string. See the command attribute for valid values.

Examples

Basic example

html

<button id="toggleBtn" commandfor="mypopover" command="toggle-popover">
  Toggle popover
</button>

<div popover id="mypopover">
  <button commandfor="mypopover" command="hide-popover">Hide popover</button>
</div>

const popover = document.getElementById("mypopover");
const toggleBtn = document.getElementById("toggleBtn");

toggleBtn.command = "show-popover";

Using custom values for commands

In this example, three buttons have been created using custom values for command. Each button targets the same image using the commandfor attribute.

html

<div class="controls">
  <button commandfor="the-image" command="--rotate-left">Rotate Left</button>
  <button commandfor="the-image" command="--reset">Reset</button>
  <button commandfor="the-image" command="--rotate-right">Rotate Right</button>
</div>

<img
  id="the-image"
  src="/shared-assets/images/examples/dino.svg"
  alt="dinosaur head rotated 0 degrees" />

.controls {
  margin-block-end: 20px;
}

An event listener is attached to the image using the command event. When one of the buttons is clicked, the listener runs code based on the custom command value assigned to the button, rotating the image and also updating it's alt text to indicate the new angle of the image.

const image = document.getElementById("the-image");

image.addEventListener("command", (event) => {
  let rotate = parseInt(event.target.style.rotate || "0", 10);
  if (event.command === "--reset") {
    rotate = 0;
    event.target.style.rotate = `${rotate}deg`;
  } else if (event.command === "--rotate-left") {
    rotate = rotate === -270 ? 0 : rotate - 90;
    event.target.style.rotate = `${rotate}deg`;
  } else if (event.command === "--rotate-right") {
    rotate = rotate === 270 ? 0 : rotate + 90;
    event.target.style.rotate = `${rotate}deg`;
  }
  event.target.alt = `dinosaur head rotated ${rotate} degrees`;
});