recharts/es6/state/types/StackedGraphicalItem.js

React charts

/**
 * Some graphical items allow data stacking. The stacks are optional,
 * so all props here are optional too.
 */

/**
 * Some graphical items allow data stacking.
 * This interface is used to represent the items that are stacked
 * because the user has provided the stackId and dataKey properties.
 */

export function isStacked(graphicalItem) {
  return 'stackId' in graphicalItem && graphicalItem.stackId != null && graphicalItem.dataKey != null;
}