Function navigateBetweenSiblings

packages/core/src/hydration/node_lookup_utils.ts:295–305

* Calculates a path between 2 sibling nodes (generates a number of `NextSibling` navigations). * Returns `null` if no such path exists between the given nodes.

(start: Node, finish: Node)

 * Returns `null` if no such path exists between the given nodes.
 */
function navigateBetweenSiblings(start: Node, finish: Node): NodeNavigationStep[] | null {
  const nav: NodeNavigationStep[] = [];
  let node: Node | null = null;
  for (node = start; node != null && node !== finish; node = node.nextSibling) {
    nav.push(NODE_NAVIGATION_STEP_NEXT_SIBLING);
  }
  // If the `node` becomes `null` or `undefined` at the end, that means that we
  // didn't find the `end` node, thus return `null` (which would trigger serialization
  // error to be produced).
  return node == null ? null : nav;
}

/**
 * Calculates a path between 2 nodes in terms of `nextSibling` and `firstChild`