A button can carry accessibility and metadata attributes that pass straight through to the HTML element. They have no visible effect, so this example shows the markup rather than a result:

• aria-label gives an accessible name when the label is only an icon
• role overrides the implied ARIA role
• tabindex sets the keyboard focus order
• data-* attaches custom data attributes for scripts
• selectedAria chooses which ARIA state selectedClass toggles

Inspect the button in your browser to see the attributes on the element.