Pre-order traversal in a Javascript Tree

Web DevelopmentFront End TechnologyJavascript

In this traversal method, the root node is visited first, then the left subtree and finally the right subtree.

We start from A, and following pre-order traversal, we first visit A itself and then move to its left subtree B. B is also traversed pre-order. The process goes on until all the nodes are visited. The output of pre-order traversal of this tree will be −

A → B → D → E → C → F → G

This is the algorithm we'll be implementing:

  • Print the node's data
  • Recursively traverse left subtree
  • Recursively traverse right subtree

Let us look at how we'd implement it in our class. 

preOrder() {
   preOrderHelper(this.root);
}

Helper function: 

Example

function preOrderHelper(root) {
   if (root !== null) {
      console.log(root.data);
      preOrderHelper(root.left);
      preOrderHelper(root.right);
   }
}

You can test this using − 

Example

let BST = new BinarySearchTree();
BST.insertRec(10);
BST.insertRec(15);
BST.insertRec(5);
BST.insertRec(50);
BST.insertRec(3);
BST.insertRec(7);
BST.insertRec(12);
BST.preOrder();

Output

This will give the output −

10
5
3
7
15
12
50
raja
Published on 28-Jun-2018 08:40:07
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