JS LinkedList

LinkedList.js

class Node {
    constructor(data, next = null) {
        this.data = data;
        this.next = next;
    }
}

class LinkedList {
    constructor() {
        this.head = null;
        this.size = 0;
    }
    // Insert at the beginning of the list

    insertAtBeginning(data) {
        this.head = new Node(data, this.head);
        this.size++;
    }

    //Insert at the end of the list

    insertLast(data){
        let node = new Node(data);
        let current;

        if(this.head === null){
            this.head = node;
        }
        else{
            current = this.head;
            while(current.next){
                current = current.next;
            }
            current.next = node;
        }
        this.size++;        
    }
    //insert at the index
    insertAt(data, index) {
        //if index is out of range
        if (index > 0 && index > this.size) {
            return;
        }
        if (index === 0) {
            this.head = new Node(data, this.head);
        }
       
        const node = new Node(data);
        let current, previous;
        current = this.head;
        let count = 0;
        while (count < index) {
            previous = current;
            current = current.next;
            count++;
        }
    }
    
    //delete at the index
    deleteAt(index) {   
        if (index > 0 && index > this.size) {
            return;
        }
        let current = this.head;
        let previous;
        let count = 0;
        if (index === 0) {

            this.head = current.next;
        }
        else {
            while (count < index) {
                previous = current;
                current = current.next;
                count++;
            }
            previous.next = current.next;
        }       
        this.size--;
    }
    //delete at the end of the list
    deleteLast() {  
        if (!this.head) {
            return;
        }
        let current = this.head;
        let previous;
        while (current.next) {
            previous = current;
            current = current.next;
        }
        previous.next = null;
        this.size--;
    }

    //delete at the index   
    deleteAt(index) {
        if (index > 0 && index > this.size) {
            return;
        }
        let current = this.head;
        let previous;
        let count = 0;
        if (index === 0) {
            this.head = current.next;
        }
        else {
            while (count < index) {
                previous = current;
                current = current.next;
                count++;
            }
            previous.next = current.next;
        }
        this.size--;
    }
    //print the linked List
    printList() {
        let temp = this.head;
        while (temp) {
            console.log(temp.data);
            temp = temp.next;
        }
    }
}

const ll = new LinkedList();