Simple double LinkedList JavaScript implementation

LinkedList.js

/**
 * LinkedList Node Class
 */
function Node(tree, value, next = null, prev = null) {
  this.tree = tree;
  this.value = value;
  this.next = next;
  this.prev = prev;
}

Node.prototype.removeSelf = function() {
  this.tree.removeNode(this);
}

Node.prototype.insertNext = function(node) {
  this.tree.insertNext(this, node);
}

Node.prototype.insertPrev = function(node) {
  this.tree.insertPrev(this, node);
}

/**
 * LinkedList Class
 */
function LinkedList() {
  this.head = null;   // no next
  this.tail = null;   // no prev
}

LinkedList.prototype.createNode = function(value) {
  return new Node(this, value);
}

LinkedList.prototype.addHead = function(node) {
  if (!this.head) {
    node.next = null;
    node.prev = null;
    this.head = this.tail = node;
    return node;
  }

  node.next = null;
  node.prev = this.head;
  this.head.next = node;
  this.head = node;
  return node;
}

LinkedList.prototype.addTail = function(node) {
  if (!this.head) {
    this.next = null;
    this.prev = null;
    this.head = this.tail = node;
    return node;
  }

  node.next = this.tail;
  node.prev = null;
  this.tail.prev = node;
  this.tail = node;
  return node;
}

LinkedList.prototype.insertNext = function(node, addingNode) {
  addingNode.prev = node;
  addingNode.next = node.next;

  if (node === this.head) {
    this.head = addingNode;
  } else {
    node.next.prev = addingNode;
  }

  node.next = addingNode;
}

LinkedList.prototype.insertPrev = function(node, addingNode) {
  addingNode.next = node;
  addingNode.prev = node.prev;

  if (node === this.tail) {
    this.tail = addingNode;
  } else {
    node.prev.next = addingNode;
  }

  node.prev = addingNode;
}

LinkedList.prototype.removeNode = function(node) {
  if (!this.head) {
    throw Error('Node not found to be removed');
  }

  const nextNode = node.next;
  const prevNode = node.prev;

  if (nextNode) {
    nextNode.prev = prevNode;
  } else {
    this.head = prevNode;
  }

  if (prevNode) {
    prevNode.next = nextNode;
  } else {
    this.tail = nextNode
  }
}

LinkedList.prototype.toString = function() {
  return [...this].map(node => node.value).join(' -> ')
}

LinkedList.prototype[Symbol.iterator] = function* () {
  let current = this.tail;

  while (current) {
    yield current;
    current = current.next;
  }
}



const list = new LinkedList();
const node1 = list.createNode(1);
const node2 = list.createNode(2);
const node3 = list.createNode(3);

list.addHead(node1);
list.addHead(node2);
list.addHead(node3);

/*
  tail          head
   1  ->  2  ->  3
  prev-> node-> next
*/

https://repl.it/@SHND1/LinkList#index.js