Singly-linked lists implementation

linked-list.js

function Node(data) {
  this.data = data;
  this.next = null
}

function LinkedList() {
  this.head = null;
  this.length = 0;
}

LinkedList.prototype.add = function (data) {
  const nodeToAdd = new Node(data);
  let nodeToCheck = this.head;

  if (!nodeToCheck) {
    this.head = nodeToAdd;
    this.length++;
    return nodeToAdd;
  }
  
  while (nodeToCheck.next) {
    nodeToCheck = nodeToCheck.next;
  }
  
  nodeToCheck.next = nodeToAdd;
  
  this.length++;
  
  return nodeToAdd;
};

LinkedList.prototype.get = function (num) {
  let nodeToCheck = this.head;
  let count = 0;

  if (num > this.length) {
    throw new Error(`The requested node doesn't exist`);
  }

  while(count < num) {
    nodeToCheck = nodeToCheck.next;
    count++;
  }

  return nodeToCheck;
}

LinkedList.prototype.remove = function (num) {
  let nodeToCheck = this.head;
  let length = this.length;
  let count = 0;
  let prevNode = null;
  
  if (num > length) {
    throw new Error(`The requested node doesn't exist`);
  }
  
  if (num === 0) {
    this.head = nodeToCheck.next;
    this.length--;
    
    return this.head;
  }
  
  while (count < num) {
    prevNode = nodeToCheck;
    nodeToCheck = nodeToCheck.next;
    count++;
  }
  
  prevNode.next = nodeToCheck.next;
  nodeToCheck = null;
  this.length--;

  return this.head;
}

const list = new LinkedList();

list.add('first');
list.add('second');
list.add('third');
list.add('fourth');

try {
  console.log(list.get(2));
  console.log(list.get(7));  
} catch(error) {
  console.log('Error:', error.message);
}