aria-pressed
Widget attributes might be mapped by a user agent to platform accessibility API state, for access by assistive technologies, or they might be accessed directly from the DOM. User agents MUST provide a way for assistive technologies to be notified when states change, either through DOM attribute change events or platform accessibility API events.
Indicates the current "pressed" state of toggle buttons. See related aria-checked and aria-selected.
Toggle buttons require a full press-and-release cycle to change their value. Activating it once changes the value to true, and activating it another time changes the value back to false. A value of mixed means that the values of more than one item controlled by the button do not all share the same value. Examples of mixed-state buttons are described in WAI-ARIA Authoring Practices [wai-aria-practices-1.1]. If the attribute is not present, the button is not a toggle button.
The aria-pressed attribute is similar but not identical to the aria-checked attribute. Operating systems support pressed on buttons and checked on checkboxes.