Binary Tree - A DFS type order

post-order.js

//     Root
//       |
//       |
// 11          12
// |           |   
// |           |
// 13  14      15  16
// |
// |
// 17 18


class TreeNode {
    constructor(value) {
      this.value = value;
      this.left = null;
      this.right = null;
    }
}

const rootNode = new TreeNode('Root');

rootNode.left = new TreeNode(11);
rootNode.right = new TreeNode(12);

rootNode.left.left = new TreeNode(13);
rootNode.left.right = new TreeNode(14);
rootNode.right.left = new TreeNode(15);
rootNode.right.right = new TreeNode(16);

rootNode.left.left.left = new TreeNode(17);
rootNode.left.left.right = new TreeNode(18);

function dfs(node) {
    if(!node) {
        return;
    }

    dfs(node.left);
    dfs(node.right);
    console.log(node.value);  
}

dfs(rootNode);