class Node {
constructor(value) {
this.value = value;
this.prev = null;
this.next = null;
}
}
class LinkedList {
constructor(value) {
this.head = new Node(value);
this.tail = this.head;
this.length = 1;
}
printList() {
const array = [];
let currentNode = this.head;
while( currentNode !== null ) {
array.push(currentNode.value);
currentNode = currentNode.next;
}
return array;
}
prepend(value) {
const newNode = new Node(value);
newNode.next = this.head;
this.head.prev = newNode;
this.head = newNode;
this.length++;
}
append(value) {
const newNode = new Node(value);
this.tail.next = newNode;
newNode.prev = this.tail;
this.tail = newNode;
this.length++;
}
insert(value, index) {
if(index >= this.length) {
return this.append(value);
}
const newNode = new Node(value);
let leader = this._traverseToIndex(index - 1);
let follower = leader.next;
leader.next = newNode;
newNode.prev = leader;
newNode.next = follower;
follower.prev = newNode;
this.length++;
}
remove(index) {
if( index >= this.length || index < 0) {
return 'out of bounds index';
}
if( index === 0 ) {
this.head = this.head.next;
}
else {
let leader = this._traverseToIndex(index -1);
let unwantedNode = leader.next;
if ( unwantedNode ) {
unwantedNode.next.prev = leader;
}
leader.next = unwantedNode.next;
}
this.length--;
}
_traverseToIndex(index){
let counter = 0;
let currentNode = this.head;
while( counter < index ) {
currentNode = currentNode.next;
counter++;
}
return currentNode;
}
}
const linkedList = new LinkedList(5);
linkedList.prepend(4)
linkedList.append(8);
linkedList.insert(6,3)
linkedList.remove(1);
console.log(linkedList.printList());
console.log(linkedList);
