A detailed cross-browser and cross-screen-reader compatibility test for the aria-haspopup ARIA attribute. Tests cover VoiceOver (iOS and macOS), Talkback, JAWS, NVDA, and Narrator across Firefox, Chrome, Edge, and Safari. Key findings: most screen readers support the attribute, but Narrator in Firefox and Chrome has issues; Talkback and older NVDA versions don't support grid, listbox, and tree values; VoiceOver with Safari omits aria-expanded announcements when combined with aria-haspopup; and various screen readers announce true vs. menu values differently. NVDA 2023.2 added support for dialog, grid, listbox, and tree keywords.
