A popup element usually appears as a block of content that is on top of other content. Authors MUST ensure that the role of the element that serves as the container for the popup content is aria-haspopup matches the role of the popup container.
For the popup element to be keyboard accessible, authors SHOULD ensure that the element that can trigger the popup is focusable, that there is a keyboard mechanism for opening the popup, and that the popup element manages focus of all its descendants as described in Managing Focus.
The aria-haspopup property is a token type. [=User agents=] MUST treat any value of aria-haspopup that is not included in the list of allowed values, including an empty string, as if the value false had been provided. To provide backward compatibility with ARIA 1.0 content, user agents MUST treat an aria-haspopup value of true as equivalent to a value of menu.
Assistive technologies SHOULD NOT expose the aria-haspopup property if it has a value of false.
Assistive technologies and user agents SHOULD NOT expose the aria-haspopup property if it has a value of false.
A
aria-haspopup is most relevant to use when there is a visual indicator in the element that triggers the popup.
For example, many controls styled with a downward pointing triangle, chevron, or ellipsis (three consecutive dots) have become standard visual indicators that a popup will display when the control is activated.