Singly Linked List Implementation in Javascript

singly-linked-list-javascript.js

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

class SinglyLinkedList{
    constructor(){
        this.length = 0;
        this.head = null;
        this.tail = null;
    }

    push(val){
        let newNode = new Node(val)
        if (this.length === 0){
            this.head = newNode;
            this.tail = newNode;
            this.length++;
        }else{
            this.tail.next = newNode;
            this.tail = newNode;
            this.length++
        }
        return this;
    }

    pop(){
        if(this.length === 0) return undefined;

        let currentNode = this.head;
        let prevNode = currentNode;

        while(currentNode.next){
            prevNode = currentNode;
            currentNode=currentNode.next;
        }

        prevNode.next = null;
        this.tail = prevNode;
        this.length--;
        return currentNode;
    }

    shift(){
        if (this.length === 0) return undefined;

        let currentHead = this.head;
        this.head = this.head.next;
        this.length--;
        return currentHead;
    }

    unshift(val){
        let newNode = new Node(val)

        if(this.length === 0){
            this.head = newNode;
            this.tail = newNode;
        }else{
            newNode.next = this.head
            this.head = newNode;
        }
        this.length++;

        return this;
    }

    get(index){
        if (this.length === 0) return undefined;

        if (index >= this.length) return undefined;

        let counter = 0;
        let currentNode = this.head;
        while(counter < index){
            currentNode = currentNode.next;
            counter++;
        }
        return currentNode;
    }

    set(index, val){
        let node = this.get(index);
        if(node){
            node.val = val;
            return node;
        }     
        return undefined;        
    }

    insert(index, val){      
        if(index < 0 || index > this.length) return false;
        if(index === 0) return !!this.unshift(val);
        if(index === this.length) return !!this.push(val)

        let newNode = new Node(val);
        let prevNode = this.get(index - 1);
        let temp = prevNode.next;
        prevNode.next = newNode
        newNode.next = temp;
        this.length++
        return true;
    }

    remove(index){
        if (index < 0 || index > this.length) return undefined;
        if(index === 0) return this.shift();
        if (index === this.length) return this.pop();

        let foundNode = this.get(index - 1);
        let toBeRemovedNode = foundNode.next;
        foundNode.next = toBeRemovedNode.next;
        toBeRemovedNode.next = null;
        this.length --
        return toBeRemovedNode;
    }
}

let list = new SinglyLinkedList();
list.push("a")
list.push("b")
list.push("c")