Function eventToTimestamp

console/src/utils/graph.ts:28–43

({
  event,
  xScale,
  startTime,
  endTime,
}: {
  event: PointerEvent | MouseEvent;
  xScale: { invert: (x: number) => Date };
  startTime: number;
  endTime: number;
})

/** Map a pointer event to its cursor timestamp in ms, clamped to `[startTime, endTime]`. Returns `null` only when the event has no coordinates. */
export function eventToTimestamp({
  event,
  xScale,
  startTime,
  endTime,
}: {
  event: PointerEvent | MouseEvent;
  xScale: { invert: (x: number) => Date };
  startTime: number;
  endTime: number;
}): number | null {
  const svgPoint = localPoint(event);
  if (!svgPoint) return null;
  const ms = xScale.invert(svgPoint.x).getTime();
  return Math.min(Math.max(ms, startTime), endTime);
}

// This function was copied and then modified from the visx XYchart:
// https://github.com/airbnb/visx/blob/6edbde496fc461094f6b3c60e8ec86c4b720b4f5/packages/visx-xychart/src/utils/findNearestDatumSingleDimension.ts#L7