Tree Traversal

1function preorderTraversal(node) {
2  if (node === null) return;
3  
4  // Visit root first
5  visit(node.value);
6  
7  // Traverse left subtree
8  preorderTraversal(node.left);
9  
10  // Traverse right subtree
11  preorderTraversal(node.right);
12}
13
14// Iterative approach
15function preorderIterative(root) {
16  if (!root) return [];
17  const stack = [root];
18  const result = [];
19  
20  while (stack.length > 0) {
21    const node = stack.pop();
22    result.push(node.value);
23    
24    // Push right first, then left
25    if (node.right) stack.push(node.right);
26    if (node.left) stack.push(node.left);
27  }
28  
29  return result;
30}