The ariaHasPopup property of the ElementInternals interface reflects the value of the aria-haspopup attribute, which indicates the availability and type of interactive popup element, such as menu or dialog, that can be triggered by an element.
Note: Setting aria attributes on ElementInternals allows default semantics to be defined on a custom element. These may be overwritten by author-defined attributes, but ensure that default semantics are retained should the author delete those attributes, or fail to add them at all. For more information see the Accessibility Object Model explainer.