Recursively find all shadow roots in a page.

SearchInTheShadows.js

/**
 * Find all elements with openned ShadowRoots
 *
 * @param {Node} e - An element that we should search for ShadowRoots within.
 * @returns {Array<Element>} Array of Elements that holds ShadowRoot
 */
const findRoots = (e = document.documentElement) => 
  [e,...e.querySelectorAll('*')]
    .filter(e => e.shadowRoot)
    .flatMap(e => [e, ...findRoots(e.shadowRoot)]);