Maintain a linked list inside a binary tree

class Node {

  constructor(value) {
    this.value = value;
  }

  insert(insertedValue) {
    if (insertedValue > this.value) {
      if (this.right) {
        this.right.insert(insertedValue);
      } else {
        this.right = new Node(insertedValue);
        if (this.left) {
          const leftNext = this.left.next;
          this.left.next = this.right;
          this.right.next = leftNext;
        } else {
          const currentNext = this.next;
          this.next = this.right;
          this.right.next = currentNext;
        }
      }
    } else if (insertedValue < this.value) {
        if (this.left) {
          this.left.insert(insertedValue);
        } else {
          this.left = new Node(insertedValue);
          const currentNext = this.next;
          this.left.next = currentNext;
          this.next = this.left;
        }
    }
  }
}


const MAX = 20;

function getRandomInt() {
  return Math.floor(Math.random() * Math.floor(MAX));
}

function traverse(node) {
  if (node) {
    console.log(node.value);
    traverse(node.left);
    traverse(node.right);
  }
}

function goNext(node) {
  if (node) {
    console.log(node.value);
    return node.next;
  }
}

const root = new Node(getRandomInt());

for (let i = 0; i < (MAX / 2); i++) {
  root.insert(i);
  root.insert(MAX - i);
}

traverse(root);

console.log('-----------');

// console.log(root.value);
const rec = {};
let tmp = root.next;
let count = 0;

console.log(count, root.value);

function go() {
  if (tmp) {
    count++;
    if (rec[tmp.value]) {
      throw new Error('duplicated!');
    } else {
      rec[tmp.value] = true;
      console.log(count, tmp.value);
      tmp = tmp.next;
      setTimeout(go, 500);
    }

  }
}

go();