Basic Queue Structure for BFS Tree

app.js

class QueueNode {
  constructor(value) {
    this.value = value;
    this.next = null;
  }
}

class Queue {
  constructor() {
    this.first = null;
    this.last = null;
    this.size = 0;
  }
  //newnode goes to back of the line/end of the queue
  enqueue(value) {
    const newNode = new QueueNode(value);
    //if queue is empty
    if (this.size === 0) {
      this.first = newNode;
      this.last = newNode;
      // add current first pointer to new first(new node), and make new node new first
    } else {
      this.last.next = newNode;
      this.last = newNode;
    }
    //add 1 to size
    this.size++;

    return this;
  }
  // dequeue nodes off the front of the line
  dequeue() {
    //if queue is empty return false
    if (this.size === 0) return false;
    //get dequeuedNode
    const dequeuedNode = this.first;
    //get new first (could be NULL if stack is length 1)
    const newFirst = this.first.next;
    //if newFirst is null, reassign last to newFirst(null)
    if (!newFirst) {
      this.last = newFirst;
    }
    //assign new first
    this.first = newFirst;
    //remove refernce to list
    dequeuedNode.next = null;
    //remove 1 from size
    this.size--;
    //return dequeuednode
    return dequeuedNode;
  }
}