izengliang

/**
 * cloneNode(true), but also clones shadow roots.
 * @param {Element}
 * @param {ShadowRoot[]} [shadowRoots] Any closed shadow roots passed here will be included.
 */
function cloneWithShadowRoots(node, shadowRoots = []) {
  function walk(node, clone) {
    let shadow = node.shadowRoot || shadowRoots.find(r => r.host === node);
    if (shadow) {
      (clone.shadowRoot || clone.attachShadow({ mode: shadow.mode })).append(...[].map.call(shadow.childNodes, c => c.cloneNode(true)));