Doubly Linked List Implementation

class Node{

constructor(value){

this.value = value;

this.next = null;

this.prev = null;

}

}

class LinkedList{

constructor(value){

this.head = {

value:value,

next: null,

prev:null

};

this.tail = this.head;

this.length = 1;

}

prepend(value){

const head = this.head;

const node = new Node(value)

this.head = node; //ref to the node obj in ram not the actual data

this.head.next = head;

head.prev = node;

this.length++;

}

append(value){

const newNode = new Node(value)

//first time this is changing the data location of head h --> {value:10, next: ref{value:5, next:null}} //second time its changing the data in ram and all refs are changing

this.tail.next = newNode; //this is a ref for newNode in ram not the actual data

newNode.prev = this.tail;

//this is a ref for newNode in ram not the actual data so when we change next time its changing the data in ram and all its ref like in head

this.tail = newNode;

this.length++;

return this;

}

insert(index, value){

if(index >= this.length){

return this.append(value);

}

var newNode = {

value:value,

next:null,

prev:null

}

var leader = this.traverseToIndex(index -1);

var nextNode = leader.next;

leader.next = newNode;

newNode.prev = leader;

newNode.next = nextNode;

nextNode.prev = newNode;

this.length++;

return this;

}

remove(index){

if(index >= this.length){

return this

}

if(index == 0){

let currentNode = this.head;

this.head = currentNode.next;

return this;

}

var currentNode = this.traverseToIndex(index)

var previousNode = this.traverseToIndex(index - 1)

previousNode.next = currentNode.next

return this.length--

}

traverseToIndex(index){

var counter = 0;

var currentNode = this.head;

while(index !== counter){

currentNode = currentNode.next;

counter++;

}

return currentNode;

}

printList(){

var arr = [];

var currentNode = this.head;

while(currentNode !== null){

arr.push(currentNode.value);

currentNode = currentNode.next;

}

return arr;

}

reverse(){

let first = this.head;

this.tail = this.head;

let second = this.head.next;

while(second) {

let temp = second.next;

first.prev = second;

second.next = first;

first = second;

second = temp;

}

this.head.next = null;

this.head = first;

this.head.prev = null;

return this;

}

}

var myLinkedList = new LinkedList(10);

myLinkedList.append(5);

myLinkedList.append(16);

myLinkedList.prepend(35);

myLinkedList.insert(1,99);

//myLinkedList.remove(10)

var arr = myLinkedList.printList();

console.log(myLinkedList);

console.log(arr);