with-children.tsx

import { withChildren } from 'skatejs';

class WithChildren extends withChildren() {
  childrenUpdated() {
    const len = this.children.length;
    this.attachShadow({ mode: 'open' }).innerHTML = `This element has ${len} ${
      len === 1 ? 'child' : 'children'
    }!`;
  }
}

customElements.define('with-children', WithChildren);