Implementation of breadth-first search algorithm on a binary search tree in JavaScript

javascript-bfs.js

class Node {
  // stores given value and points to nothing
  constructor (value) {
    this.value = value
    this.left = null
    this.right = null
  }
}

class Tree {
  // initially just has a root variable with null assigned
  constructor () {
    this.root = null
  }

  // helper functions

  // starting from root, traverses through a tree/subtree and
  // inserts new node depending on its value
  traverseAndInsert = (root, node) => {
    // if new node value less than root
    if (node.value < root.value) {
      // if left node null, make new node the left node
      if (root.left === null) root.left = node
      // else get traverseAndInsert to find the correct place in left subtree to insert new node
      else this.traverseAndInsert(root.left, node)
     // if new node value greater than root
    } else {
      // if right node null, make new node the right node
      if (root.right === null) root.right = node
      // else get traverseAndInsert to find the correct place in right subtree to insert new node
      else this.traverseAndInsert(root.right, node)
    }
  }

  // end of helper functions

  // to insert nodes to tree
  insert = value => {
    // create new node with given value
    let node = new Node(value)

    // if root null, make new node the root
    if (this.root === null) this.root = node
    // if not, get traverseAndInsert to find the correct place to insert new node
    else this.traverseAndInsert(this.root, node)
  }

  // -------- BFS ----------

  traverse = root => {
    // have a queue structure 
    // using an array for simplicity
    let queue = []

    if (root === null) return null

    // enqueue root of tree
    queue.push(root)

    // keep dequeueing nodes you visit and enqueueing their children 
    while (queue.length > 0) {
      // get value from front item of queue
      console.log(queue[0].value)
      
      // enqueue children
      if (queue[0].left) queue.push(queue[0].left)
      if (queue[0].right) queue.push(queue[0].right)

      // dequeue front item
      queue.shift()
    }
  }
}

// tests

// let tree = new Tree()

// tree.insert(7)
// tree.insert(24)
// tree.insert(9)
// tree.insert(36)
// tree.insert(21)

// tree.traverse(tree.root)