Combobox with a11y-compliant roving tabindex

Keyboard-controllable, and clicking on the label focuses the input.

This uses a tabindex to manage focus between the input and the selected item in the popup.

WAI-ARIA checklist

• role=combobox(optional)
• aria-autocomplete(optional)

  Not applicable as this does not have search functionality

• aria-expanded(optional)
• role=listbox(optional)

  Set on the popup

• aria-haspopup(optional)

  Not required if the popup role is already listbox

• aria-activedescendant(optional)

  Not applicable