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);
