元素：computedStyleMap() 方法

computedStyleMap()

<p>
  <a href="https://example.com">Link</a>
</p>
<dl id="regurgitation"></dl>

a {
  --color: red;
  color: var(--color);
}

// get the element
const myElement = document.querySelector("a");

// get the <dl> we'll be populating
const stylesList = document.querySelector("#regurgitation");

// Retrieve all computed styles with computedStyleMap()
const allComputedStyles = myElement.computedStyleMap();

// iterate through the map of all the properties and values, adding a <dt> and <dd> for each
for (const [prop, val] of allComputedStyles) {
  // properties
  const cssProperty = document.createElement("dt");
  cssProperty.appendChild(document.createTextNode(prop));
  stylesList.appendChild(cssProperty);

  // values
  const cssValue = document.createElement("dd");
  cssValue.appendChild(document.createTextNode(val));
  stylesList.appendChild(cssValue);
}