ES6 classes are very handy feature of javascript. Main advantage is that it makes code more readable than it prototypal counterpart. I know Classes are syntatic suger over the prototypal implementation.

Still its a great addition to the language. As it make code more modular and maintainable.

Here we are going to try to make a Linked list implementation using ES6 Classes. Its not really a tutorial of classes or LinkedList, but to show how easy code becomes with use of classes.

Here we go…

First we going to Node class of the LinkedList.

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

It becomes very easy to maintain if the node class is maintained separately.
We can always add more methods to this class, even we can extend the existing class for new types as needed.

Let’s define out LinkedList class

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

This is as simple as that.
We are going to add more methods for LinkedList to be more functional.

Lets try to define add method to it.

• If head is empty assign the first node as head node.
• If head is not empty, traverse through all the nodes where the next is empty.
• Assign the new node as the next node of the last node.

  add(node){
    if(this.head === null){
      this.head = node;
    }else{
      let current = this.head;
      while(current.next != null){
        current = current.next;
      }
      current.next = node;
    }
  }

Next, Lets try to add print method to LinkedList before we go to test it

  print(){
    let current = this.head;
    while(current){
      console.log(current.data);
      current = current.next;
    }
  }

Our LinkedList implementation to add and print is ready. To sum it up, it will be like.

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

  add(node){
    if(this.head === null){
      this.head = node;
    }else{
      let current = this.head;
      while(current.next != null){
        current = current.next;
      }
      current.next = node;
    }
  }

  print(){
    let current = this.head;
    while(current){
      console.log(current.data);
      current = current.next;
    }
  }
}

Lets test out implementation with following code.

let linkedList = new LinkedList();

// add few nodes
linkedList.add(new Node(1));
linkedList.add(new Node(2));
linkedList.add(new Node(3));

//print linked list.
linkedList.print();