Tree Data Structure
A tree is a collection of nodes connected by some edges. Conventionally, each node of a tree holds some data and reference to its children.
Binary Search Tree
Binary Search tree is a binary tree in which nodes that have lesser value are stored on the left while the nodes with a higher value are stored at the right.
For instance, visual representation of a valid BST is −
25 / \ 20 36 / \ / \ 10 22 30 40
Let’s now implement our very own Binary Search Tree in JavaScript language.
Step 1: The Node Class
This class will represent a single node present at various points in the BST. A BST is nothing but a collection of nodes storing data and child references placed according to the rules described above.
class Node{ constructor(data) { this.data = data; this.left = null; this.right = null; }; };
To create a new Node instance, we can call this class like this with some data −
const newNode = new Node(23);
This will create a new Node instance with data set to 23 and left and right reference both being null.
Step 2: The Binary Search Tree Class:
class BinarySearchTree{ constructor(){ this.root = null; }; };
This will create the Binary Search Tree class which we can call with the new keyword to make a tree instance.
Now as we are done with the basic stuff let’s move on to inserting a new node at the right place (according to the rules of BST described in definition).
Step 3: Inserting a Node in BST
class BinarySearchTree{ constructor(){ this.root = null; } insert(data){ var newNode = new Node(data); if(this.root === null){ this.root = newNode; }else{ this.insertNode(this.root, newNode); }; }; insertNode(node, newNode){ if(newNode.data < node.data){ if(node.left === null){ node.left = newNode; }else{ this.insertNode(node.left, newNode); }; } else { if(node.right === null){ node.right = newNode; }else{ this.insertNode(node.right,newNode); }; }; }; };
Example
Full Binary Search Tree Code:
class Node{ constructor(data) { this.data = data; this.left = null; this.right = null; }; }; class BinarySearchTree{ constructor(){ this.root = null; } insert(data){ var newNode = new Node(data); if(this.root === null){ this.root = newNode; }else{ this.insertNode(this.root, newNode); }; }; insertNode(node, newNode){ if(newNode.data < node.data){ if(node.left === null){ node.left = newNode; }else{ this.insertNode(node.left, newNode); }; } else { if(node.right === null){ node.right = newNode; }else{ this.insertNode(node.right,newNode); }; }; }; }; const BST = new BinarySearchTree(); BST.insert(1); BST.insert(3); BST.insert(2);