target is typed as a Node rather than a UIWidget deliberately:
§72 lists focus and blur as input events on nodes, and a later keyboard or
DOM-mirror focus source must be able to emit these same keys for a node that
is not a widget. related is the DOM's relatedTarget — the node losing the
focus this one gained, or gaining the focus this one lost — and is null
when there is none.
Payload of the
focusandblurevents (§72, §75).targetis typed as a Node rather than aUIWidgetdeliberately: §72 lists focus and blur as input events on nodes, and a later keyboard or DOM-mirror focus source must be able to emit these same keys for a node that is not a widget.relatedis the DOM'srelatedTarget— the node losing the focus this one gained, or gaining the focus this one lost — and isnullwhen there is none.