Design a Singly Linked List

singly-linked-list.js

class ListNode {
    constructor(val) {
        this.val = val;
        this.next = null;
    }
}

class LinkedList {
    constructor() {
        this.head = null;
        this.tail = this.head;
    }

    /**
     * @param {number} index
     * @return {number}
     */
    get(index) {
        let currentNode = this.head;
        let currentIndex = 0;
        
        while(currentNode) {
            if (currentIndex === index) {
                return currentNode.val;
            }

            currentNode = currentNode.next;
            currentIndex++;
        }

        return -1;
    }

    /**
     * @param {number} val
     * @return {void}
     */
    insertHead(val) {
        const newNode = new ListNode(val);
        newNode.next = this.head;
        this.head = newNode;

        // List was empty
        if (!newNode.next) {
            this.tail = newNode;
        }
    }

    /**
     * @param {number} val
     * @return {void}
     */
    insertTail(val) {
        const newNode = new ListNode(val);

        // Empty list
        if (!this.head) {
            this.head = newNode;
            this.tail = this.head;
        }
        else {
            this.tail.next = newNode;
            this.tail = newNode;
        }

    }

    /**
     * @param {number} index
     * @return {boolean}
     */
    remove(index) {
        let i = 0;
        let curr = this.head;

        // Removing head case
        if (index === 0 && this.head) {
            this.head = this.head.next;
            return true;
        }

        while (i < index - 1 && curr) {
            i++;
            curr = curr.next;
        }

        // Remove the node ahead of curr
        if (curr && curr.next) {
            if (curr.next === this.tail) {
                this.tail = curr;
            }
            curr.next = curr.next.next;
            return true;
        }
        return false;
    }

    /**
     * @return {number[]}
     */
    getValues() {
        let currentNode = this.head;

        const values = [];
        while (currentNode) {
            values.push(currentNode.val);

            currentNode = currentNode.next;
        }

        return values;
    }
}