Minor code style fixes for DoublyLinkedList.

Author: trekhleb

src/data-structures/doubly-linked-list/DoublyLinkedList.js

@@ -23,9 +23,9 @@ export default class DoublyLinkedList {
  // Make new node to be a head.
  const newNode = new DoublyLinkedListNode(value, this.head);
 
- // If there is head, then it won't be head anymore
- // Therefore, make its previous reference to be new node (new head)
- // Then mark the new node as head
+ // If there is head, then it won't be head anymore.
+ // Therefore, make its previous reference to be new node (new head).
+ // Then mark the new node as head.
  if (this.head) {
  this.head.previous = newNode;
  }
@@ -57,7 +57,7 @@ export default class DoublyLinkedList {
  // Attach new node to the end of linked list.
  this.tail.next = newNode;
 
- // Attach current tail to the new node's previous reference
+ // Attach current tail to the new node's previous reference.
  newNode.previous = this.tail;
 
  // Set new node to be the tail of linked list.
@@ -83,10 +83,10 @@ export default class DoublyLinkedList {
  deletedNode = currentNode;
 
  if (deletedNode === this.head) {
- // set head to second node, which will become new head
+ // Set head to second node, which will become new head.
  this.head = deletedNode.next;
 
- // set new head's previous to null
+ // Set new head's previous to null
  if (this.head) {
  this.head.previous = null;
  }