selector

Type:
<string> | <string[]>

Values:
It defines the you want to pick from the HTML markup over the url:
It's equivalent to and any can be specified, such as:
  • An HTML tag (e.g., 'img').
  • A CSS class or pseudo class, id or data-attribute (e.g., '#avatar').
  • A combination of both (e.g., 'img:first').
If you pass a collection of selectors, they are considered as fallbacks values:
Using mulitple selectors makes the data rule more generic.
The position into the collection matters: The first data rule that returns a truthy value after applying type will be used, discarding the rest of the selectors.