useUpdateNodeInternals
When you are programatically changing the number or the position of handles inside a custom node you need to notify React Flow about it with the useUpdateNodeInternals hook. It also updates the internal dimensions of a node. The hook returns a function that expects a string (node id) as a parameter.
caution
This hook can only be used if the component that uses it, is wrapped with a ReactFlowProvider or if it's a children of the <ReactFlow /> component.
Usage​
import { useUpdateNodeInternals } from 'react-flow-renderer';
function UpdateNodeButton() {
  const updateNodeInternals = useUpdateNodeInternals();
  return <button onClick={() => updateNodeInternals('node-id')}></button>;
}
Typescript​
The returned function has the type UpdateNodeInternal. Which is (nodeId: string) => void;:
useUpdateNodeInternals(): UpdateNodeInternals