Linked List in node.js

 class Node {

constructor(data) {

this.data = data

this.next = null

}

}

class LinkedList {

constructor(head = null) {

this.head = head

}

appendNode(newNode) {

var node = this.head;

if (node == null) {

this.head = newNode

} else {

while (node.next) {

node = node.next

}

node.next = newNode

}

}

insertAt(index, newNode) {

if (index == 0) {

var tempVal = this.head

newNode.next = tempVal

this.head = newNode

} else {

var i = 1

var firstNode = this.head

while (i < index - 1) {

firstNode = firstNode.next

if (firstNode == null) {

console.log("Index out of bound")

return

}

i++

}

var tempVal = firstNode.next

newNode.next = tempVal

firstNode.next = newNode

}

}

listSize() {

var firstNode = this.head;

var i = 0;

while (firstNode) {

firstNode = firstNode.next

i++

}

return i;

}

isEmpty() {

return (this.head == null)

}

getFirst() {

return this.head;

}

getLast() {

var firstNode = this.head

while (firstNode.next) {

firstNode = firstNode.next

}

return firstNode

}

removeFrom(index) {

if (index == 0) {

var tempVal = this.head

this.head = tempVal.next

} else {

var i = 0;

var firstNode = this.head;

var previousNode = null;

while (i < index - 1) {

previousNode = firstNode

firstNode = firstNode.next

i++

if (firstNode == null) {

console.log("Index Out of bound")

return;

}

}

if (previousNode == null) {

this.head = firstNode.next

} else {

previousNode.next = firstNode.next

}

}

}

getNode(index) {

if (index == 0) {

return this.head

} else {

var firstNode = this.head

var i = 0;

while (i < index - 1) {

firstNode = firstNode.next

i++

}

return firstNode

}

}

clear() {

this.head = null;

}

reverse() {

let previousNode = null

let currentNode = this.head;

if (currentNode == null) return;

let nextNode = null

while (currentNode) {

nextNode = currentNode.next;

currentNode.next = previousNode

previousNode = currentNode

currentNode = nextNode

}

this.head = previousNode

}

indexOf(data) {

var firstNode = this.head

var j = 0

while (firstNode) {

if (firstNode.data == data) {

return j

}

firstNode = firstNode.next

j++

}

}

printList() {

let node = this.head;

process.stdout.write("HEAD->")

while (node) {

process.stdout.write(node.data + "->");

node = node.next;

}

console.log("NULL");

}

}

let myList = new LinkedList();

let node = new Node(5);

myList.appendNode(node);

myList.appendNode(new Node(11));

myList.appendNode(new Node(7));

myList.appendNode(new Node(17));

myList.appendNode(new Node(87));

myList.printList();

myList.insertAt(6, new Node(21));

myList.printList();

myList.removeFrom(6)

myList.printList();

var size = myList.listSize()

console.log("size", size)

var n = myList.getNode(2)

console.log("item at index 2", n)

// myList.clear()

// var size1 = myList.listSize()

// console.log("size", size1)

myList.reverse()

myList.printList();

var y = myList.indexOf(7)

console.log("indexof 7", y)

var lastNode = myList.getLast()

console.log("lastNode",lastNode)