linked-list.js

class Node {
    constructor(data) {
        this.data = data;
        this.next = null;
    }
}
class LinkedList {
    constructor () {
        this.head = null;
        this.size = 0;
    }
    prepend (data) {
        const newHead = new Node(data);
        newHead.next = this.head;
        this.head = newHead;
        this.size++
    }
    append(data) {
        if(this.head == null) {
            this.head = new Node(data);
            this.size++
            return;
        }
        let currentNode = this.head;
        while(currentNode.next != null) {
            currentNode = currentNode.next;
        }
        currentNode.next = new Node(data);
        this.size ++
    }

    deleteValue(data) {
        if (this.head == null) return; 

        if(this.head.data == data) {
            this.head = this.head.next;
            this.size--;
            return;
        }

        let currentNode = this.head;
        while(currentNode.next != null) {
            if(currentNode.next.data == data) {
                currentNode.next = currentNode.next.next;
                this.size--
                return data;
            }
            currentNode = currentNode.next;
        }
    }

    getNth(index) {
        if(index < 0 || index >= this.size) {
            return;
        }
        let currentNodeIndex = -1;
        let currentNode = this.head;

        console.log(this.head.data)

        while(currentNodeIndex < index) {
            currentNodeIndex++

            if(currentNodeIndex === index) {
                return currentNode.data;
            }
            currentNode = currentNode.next;
        }
    }

    indexOf(data) {
      let index = -1;
      let currentNode = this.head;
      while(currentNode) {
        index++
        if(currentNode.data == data) {
            return index;
        }
        currentNode = currentNode.next
      }
    }

    addAt(index, data){
        if(index < 0 || index > this.size) {
            return;
        }
        let currentNode = this.head;
        let currentIndex = 0;
        let previousNode;
        let node = new Node(data);

        if(index == 0) {
            node.next = currentNode;
            this.head = node;
            this.size++
        }else {
            while(currentIndex < index) {
                currentIndex++;
                previousNode = currentNode;
                currentNode = currentNode.next
            }
            node.next = currentNode;
            previousNode.next = node;
            this.size++
        }
    }

    removeAt (index) {
        let currentNode = this.head;
        let previousNode;
        let currentIndex = 0;

        if(this.head == null) return;

        if(index == 0) {
            this.head = currentNode.next;
            this.size--;
        }else {
            while(currentIndex < index) {
                currentIndex++
                previousNode = currentNode;
                currentNode = currentNode.next
            }
            previousNode.next = currentNode.next;
            this.size--;
        }
    }
}

const list = new LinkedList();

list.prepend(400)
list.append(500)
list.addAt(1, 200)
// list.deleteValue(200)
list.removeAt(1);
console.log("nth element:", list.getNth(1))
console.log("index of data:", list.indexOf(500))
console.log(list.size);