===== ISTEM =====
Solve the following programming task.

TASK: Tree Level Order Traversal (BFS)

Write a function 'levelOrder(root)' that traverses the given node tree (node: { val, children: [] }) breadth-first and returns an array containing the values of the elements at each level.

STARTER CODE (javascript):
function levelOrder(root) {
  // Write your code here
}

module.exports = { levelOrder };


RULES:
- Keep the function name and signature EXACTLY as given.
- Return working code only. No explanations.
- Put the code in a single ``` block.
- Try to solve it first. If you genuinely cannot, write only this single
  line instead of producing faulty code: CANNOT_SOLVE

===== HAM YANIT =====
```javascript
function levelOrder(root) {
  const result = [];
  if (!root) return result;

  let queue = [root];

  while (queue.length > 0) {
    const levelValues = [];
    const nextQueue = [];

    for (const node of queue) {
      levelValues.push(node.val);
      if (node.children && node.children.length > 0) {
        nextQueue.push(...node.children);
      }
    }

    result.push(levelValues);
    queue = nextQueue;
  }

  return result;
}

module.exports = { levelOrder };
```