The current navigation position, or null when nothing is
selected
The ID of the active layer/trace
The current row index (e.g., dataset index)
The current column index (e.g., data point index)
OptionalpointIndices?: readonly number[]Present only for a point cloud (scatter, volcano,
manhattan), whose selection is a set of points rather than a cell of a
grid: the indices into that layer's data array — as the producer supplied
it — of every point the highlight covers. When it is present row and
col are both -1, because no row/column pair can name the selection, and
a consumer that bounds-checks them (as it must) then clears the overlay
rather than outlining an arbitrary mark.
Callback invoked when the active data point changes during navigation. Used by canvas-based charting libraries (e.g., Chart.js) for visual highlighting.
nullmeans no data point is active — the cursor has left a subplot for the figure lobby of a multi-panel chart. A consumer drawing an overlay must clear it, since there is no other signal that the selection ended: without one, the last point's highlight stays on screen and follows the user to another panel, pointing at a chart it does not belong to.