See: https://codesandbox.io/s/magical-wiles-l7e5q8?file=%2Fsrc%2Findex.js

DoublyLinkedList.js

class DoublyLinkedListNode {
  constructor(value) {
    this.value = value;
    this.head = null;
    this.tail = null;
  }

  valueOf() {
    return this.value;
  }
}

class DoublyLinkedList {
  constructor(values = []) {
    this.head = null;
    this.tail = null;
    this.length = 0;

    for (const value of values) {
      this.push(value);
    }
  }

  unshift(value) {
    const node = new DoublyLinkedListNode(value);

    if (!this.head) {
      this.head = node;
      this.tail = node;
      return;
    }

    const currentHead = this.head;
    currentHead.head = node;
    node.tail = currentHead;
    this.head = node;

    this.length++;
  }

  shift() {
    const currentHead = this.head;
    const value = currentHead ? currentHead.value : null;

    const newHead = currentHead.tail;
    newHead.head = null;
    this.head = newHead;

    this.length--;

    return value;
  }

  push(value) {
    const node = new DoublyLinkedListNode(value);

    if (!this.tail) {
      this.head = node;
      this.tail = node;

      this.length++;

      return;
    }

    const currentTail = this.tail;
    currentTail.tail = node;
    node.head = currentTail;
    this.tail = node;

    this.length++;
  }

  pop() {
    if (!this.tail) {
      return null;
    }

    const currentTail = this.tail;
    const value = currentTail.value;

    const previousNode = currentTail.head;
    previousNode.tail = null;
    this.tail = previousNode;

    this.length--;

    return value;
  }

  *[Symbol.iterator]() {
    let currentNode = this.head;
    if (!currentNode) {
      return;
    }

    while (currentNode) {
      yield currentNode.value;
      currentNode = currentNode.tail;
    }
  }
}

const list = new DoublyLinkedList();
list.push(1);
list.push(2);
list.push(3);
list.pop();
for (let v of list) {
  console.log(v);
}

console.log(list);

Can this be made faster at seeking/peeking at a node when given a key/value by adding a Map to this? What about duplicates? Do we key by value or create an additional key?