Tree Traversal Inorder Left Root Right in DSA Javascript - Build from Scratch

Tree Traversal Inorder Left Root Right

📖 Scenario: You have a simple family tree where each person can have a left child and a right child. You want to visit each person in a special order: first the left child, then the person themselves, and then the right child. This is called inorder traversal.

🎯 Goal: Build a program that creates a small tree, sets up a list to store the traversal result, writes the inorder traversal function, and finally prints the order in which people are visited.

📋 What You'll Learn

Create a tree node structure with value, left, and right properties

Build a tree with exactly these nodes and connections: root 'A', left child 'B', right child 'C', left child of 'B' is 'D', right child of 'B' is 'E'

Create an empty array called result to store traversal output

Write a function called inorderTraversal that visits nodes in left-root-right order and adds their values to result

Call inorderTraversal with the root node

Print the result array after traversal

💡 Why This Matters

🌍 Real World

Tree traversal is used in many real-world applications like searching family trees, organizing files, and parsing expressions.

💼 Career

Understanding tree traversal is important for software developers working with data structures, databases, and algorithms.

1

Create the tree nodes and build the tree

Create variables root, nodeB, nodeC, nodeD, and nodeE as objects with value, left, and right properties. Set their values to 'A', 'B', 'C', 'D', and 'E' respectively. Connect them so that root.left = nodeB, root.right = nodeC, nodeB.left = nodeD, and nodeB.right = nodeE. All other children should be null.

DSA Javascript

// Create tree nodes and connect them
// Your code here

Hint

Each node is an object with value, left, and right. Connect them by assigning the left and right properties.

2

Create an empty array to store traversal results

Create an empty array called result to hold the values of nodes visited during inorder traversal.

DSA Javascript

const nodeD = { value: 'D', left: null, right: null };
const nodeE = { value: 'E', left: null, right: null };
const nodeB = { value: 'B', left: null, right: null };
const nodeC = { value: 'C', left: null, right: null };
const root = { value: 'A', left: null, right: null };
root.left = nodeB;
root.right = nodeC;
nodeB.left = nodeD;
nodeB.right = nodeE;

// Create an empty array called result
// Your code here

Hint

Use const result = []; to create an empty array.

3

Write the inorder traversal function

Write a function called inorderTraversal that takes a node as input. If the node is not null, first call inorderTraversal on the node's left child, then add the node's value to the result array, and finally call inorderTraversal on the node's right child.

DSA Javascript

const nodeD = { value: 'D', left: null, right: null };
const nodeE = { value: 'E', left: null, right: null };
const nodeB = { value: 'B', left: null, right: null };
const nodeC = { value: 'C', left: null, right: null };
const root = { value: 'A', left: null, right: null };
root.left = nodeB;
root.right = nodeC;
nodeB.left = nodeD;
nodeB.right = nodeE;

const result = [];

// Write the inorderTraversal function here
// Your code here

Hint

Use a function with a check for null. Visit left child first, then add current node's value, then visit right child.

4

Call the traversal and print the result

Call inorderTraversal with the root node. Then print the result array using console.log(result).

DSA Javascript

const nodeD = { value: 'D', left: null, right: null };
const nodeE = { value: 'E', left: null, right: null };
const nodeB = { value: 'B', left: null, right: null };
const nodeC = { value: 'C', left: null, right: null };
const root = { value: 'A', left: null, right: null };
root.left = nodeB;
root.right = nodeC;
nodeB.left = nodeD;
nodeB.right = nodeE;

const result = [];

function inorderTraversal(node) {
    if (node !== null) {
        inorderTraversal(node.left);
        result.push(node.value);
        inorderTraversal(node.right);
    }
}

// Call inorderTraversal with root and print result
// Your code here

Hint

Call the function with root and then print result with console.log(result).