How do I access a property on a base class that is for a web component?

Question

I would like to set the html namespace for the component on the Base class, but it seems you can't do NavBar.ns without creating an instance, which makes the web component not render.

import Base from './Base.js';

class NavBar extends Base {
  constructor() {
    super();
  }

  connectedCallback() {
    console.log('ns', this.ns);
    this.innerHTML = '...';
  }
}

console.log('ns2', NavBar.ns);  // undefined here
customElements.define(`${NavBar.ns}-navbar`, NavBar);

Base.js:

class Base extends HTMLElement {
  constructor() {
    super();
    this.ns = 'wce';
  }


}

export default Base;