Binary search tree

bst.js

class Node {
  constructor(val) {
    this.val = val;
    this.left = undefined;
    this.right = undefined;
    this.parent = undefined;
  }
}

class BST {
  counstructor() {
    this.head = undefined;
  }

  add(val) {
    if (!this.head) {
      this.head = new Node(val);
      return this;
    }

    let current = this.head;

    while (current) {
      if (val === current.val) {
        break;
      }

      let parent = current;
      if (val < current.val) {
        if (!current.left) {
          current.left = new Node(val);
          current.left.parent = parent;
          break;
        } else {
          current = current.left;
        }
      }

      if (val > current.val) {
        if (!current.right) {
          current.right = new Node(val);
          current.right.parent = current;
        } else {
          current = current.right;
        }
      }

    }

    current = new Node(val);
  }

  BFS() {
    let queue = [];
    let data = [];
    queue.push(this.head);

    while (queue.length) {
      let current = queue.shift();
      data.push(current.val);

      if (current.left) {
        queue.push(current.left);
      }

      if (current.right) {
        queue.push(queue.right);
      }
    }

    return data;
  }

}

let tree = new BST();

tree.add(5);
tree.add(4);
tree.add(2);

console.log(tree.BFS());