ariamultiselectable

aria-multiselectable is an ARIA state that can be applied to container elements with roles such as listbox or tree to indicate that the control supports selecting more than one item at a time. When set to true, multiple options can be selected; when omitted or set to false, the control is treated as single-select. The attribute is used together with individual item roles, typically role="option" inside a listbox or role="treeitem" inside a tree, with each item exposing its selection state through aria-selected.

In a multi-selectable listbox or tree, users interact with the items using keyboard and pointer input. Typical patterns include navigating with the arrow keys and toggling the selection of the focused item with Space or Enter. Shift can be used to select a range of items, while Ctrl (Cmd on macOS) can be used to toggle independent items without affecting others. Implementations should keep aria-selected in sync with the visual selection state and ensure that focus management remains clear.

Accessibility considerations include ensuring that the visible selection cues align with aria-selected, providing clear labels and instructions, and ensuring compatibility with assistive technologies. Developers should test that screen readers announce selection changes and that the control behaves consistently across platforms. aria-multiselectable is part of the WAI-ARIA guidance for complex widgets and should be used only when the underlying UI truly supports multiple selections, to avoid confusing users with misleading semantics.