get fragment() {
    const href = this.href;
    if (typeof href === 'string') {
      const indexOfFragment = href.indexOf('#');
      if (indexOfFragment === -1) {
        return '';
      } else {
        return href.substr(indexOfFragment);
      }
    }
  }
Get or set the fragment identifier part of the href of the relation.

Setting a fragment with a non-empty value requires the value to begin with `#`

@type {String}