ES6 Singly Linked List

singly-linked-list.js

class Node {
  constructor(data) {
    this.data = data
    this.next = null
  }
}
 
class SinglyList {
  constructor() {
    this._length = 0;
    this.head = null;
  }
 
  add(value) {
    const node = new Node(value)
    let currentNode = this.head;
 
    // 1st use-case: an empty list
    if (!currentNode) {
        this.head = node;
        this._length++;
 
        return node;
    }
 
    // 2nd use-case: a non-empty list
    while (currentNode.next) {
        currentNode = currentNode.next;
    }
 
    currentNode.next = node;
 
    this._length++;
     
    return node;
  }
  
  searchNodeAt(position) {
    let currentNode = this.head
    let length = this._length
    let count = 1
    const message = {failure: 'Failure: non-existent node in this list.'}
 
    // 1st use-case: an invalid position
    if (length === 0 || position < 1 || position > length) {
        throw new Error(message.failure)
    }
 
    // 2nd use-case: a valid position
    while (count < position) {
        currentNode = currentNode.next
        count++
    }
 
    return currentNode
  }
 
  remove(position) {
    let currentNode = this.head
    let length = this._length
    let count = 0
    const message = {failure: 'Failure: non-existent node in this list.'}
    let beforeNodeToDelete = null
    let nodeToDelete = null
    let deletedNode = null
 
    // 1st use-case: an invalid position
    if (position < 0 || position > length) {
        throw new Error(message.failure)
    }
 
    // 2nd use-case: the first node is removed
    if (position === 1) {
        this.head = currentNode.next
        deletedNode = currentNode
        currentNode = null
        this._length--
         
        return deletedNode
    }
 
    // 3rd use-case: any other node is removed
    while (count < position) {
        beforeNodeToDelete = currentNode
        nodeToDelete = currentNode.next
        count++;
    }
 
    beforeNodeToDelete.next = nodeToDelete.next
    deletedNode = nodeToDelete
    nodeToDelete = null
    this._length--
 
    return deletedNode
  }
}

export default SinglyList

Original code can be found here: https://code.tutsplus.com/articles/data-structures-with-javascript-singly-linked-list-and-doubly-linked-list--cms-23392