ShadowRoot: clonable property

The clonable read-only property of the ShadowRoot interface returns true if the shadow root is clonable, and false otherwise.

When the value is true, a shadow host cloned with Node.cloneNode() or Document.importNode() will include a copy of the shadow root.

By default the value is false. It can be set to true using the clonable option of the Element.attachShadow() method or by setting the shadowrootclonable attribute of the <template> element that is being used to declaratively attach a shadow root.

const host = document.createElement("div");
const shadowRoot = host.attachShadow({
  mode: "open",
  clonable: true,
});

shadowRoot.clonable;
// true