Invert Binary Tree

main.js

/**
 * @param {TreeNode} node
 * @return {TreeNode} 
 */
const invert = node => {
    if(!node) {
        return null;
    }
    
    const temp = node?.left;
    node.left = node?.right;
    node.right = temp;
    
    node.left = invert(node.left);
    node.right = invert(node.right);
    
    return node;
}

/**
 * @param {TreeNode} root
 * @return {TreeNode}
 */
const invertTree = root => {
    const output = invert(root);
    return output;
};

This was for https://leetcode.com/problems/invert-binary-tree/