===== 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) {
  if (!root) return [];
  const result = [];
  const queue = [root];
  while (queue.length) {
    const levelSize = queue.length;
    const levelVals = [];
    for (let i = 0; i < levelSize; i++) {
      const node = queue.shift();
      levelVals.push(node.val);
      if (Array.isArray(node.children)) {
        for (const child of node.children) {
          if (child) queue.push(child);
        }
      }
    }
    result.push(levelVals);
  }
  return result;
}

module.exports = { levelOrder };
```
