Singly Linked List in JavaScript

Linked Lists in Javascript are a data structure similar to arrays, consisting of a sequence of nodes where each node contains a value and a reference to the next node in the sequence. These lists have head, tail, and length properties, where head is the place or node where the recent value is added, and tail is the last node.
Singly linked lists are a type of linked list where each node only has a reference to the next node in the sequence.

In the following example we will show a Singly linked list with its methods to add, remove, show, etc.
Two classes will be created, a node class that will reference the model for the nodes and a linked list class that will be the model for the list and will include all the necessary methods for the list to work.

<script>
  class Node {
      constructor(element) {
        this.element = element;
        this.next = null;            
      }
  }
  class SinglyLinkedList{
      constructor(){
        this.head = null;
        this.tail = null;
        this.length = 0;
      }
      add(element){
        let node = new Node(element);
        if(!this.head){
          this.head = node;
          this.tail = this.head;
        }else{
          this.tail.next = node;
          this.tail = node;
        }
        this.length++;
        return this;
      }
      printLinkedList(){
        var current = this.head;
        var value = "";
        while (current) {
          value += current.element+" ";
          current = current.next;
        }
        console.log(value);
      }
      removeElement(element){
        var currentEl = this.head;
        var prevEl = null;
        while (currentEl != null) {
          if (currentEl.element === element) {
            if (prevEl == null) {
              this.head = currentEl.next;
            } else {
              prevEl.next = currentEl.next;
            }
            this.size--;
            return currentEl.element;
          }
          prevEl = currentEl;
          currentEl = currentEl.next;
        }
        return -1;
      }
    getNodeByIndex(index){
      var value = "";
      if(index < 0 || index >= this.length){
        console.log("There is no node for that index");
      }
      var counter = 0;
      var current = this.head;
      while(counter !== index){
        current = current.next;
        value = current.element;
        counter++;
      }
      console.log(value);
    }
  }
  //Running example
  var myList = new SinglyLinkedList();
  //adding elements
  myList.add(5);
  myList.add(7);
  //Printing on console
  console.log("Adding 5 and 7. Printing on console");
  myList.printLinkedList();
  //Deleting element
  console.log("Deleting element 5");
  myList.removeElement(5);
  //Printing on console
  console.log("Adding 9 and 10");
  myList.add(9);
  myList.add(10);
  console.log("Printing Linked List on console");
  myList.printLinkedList();
  console.log("Printing node by index 2");
  myList.getNodeByIndex(2);
</script>