Linkedlist

linkedList.js

// source https://codeburst.io/linked-lists-in-javascript-es6-code-part-1-6dd349c3dcc3
class Node{
    constructor(data, next = null){
        this.data = data,
        this.next = next
    }
}

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

// A list object is created with a property head, currently pointing at null
let list = new LinkedList();

// Singly list - inserting at the beginning of a singly list
LinkedList.prototype.insertAtBeginning = function(data){
  // A newNode object is created with property data and next = null    
    let newNode = new Node(data);
  // The pointer next is assigned head pointer so that both pointers now point at the same node.    
   newNode.next = this.head;
  // As we are inserting at the beginning, the head pointer needs to now point at the newNode. 
    this.head = newNode;    
    return this.head;
}

// Singly list - inserting at the end of a singly list
LinkedList.prototype.insertAtEnd = function(data){
  // A newNode object is created with property data and next=null
    let newNode = new Node(data);
  // When head = null i.e. the list is empty, then head itself will point to the newNode.    
      if(!this.head){
        this.head = newNode;
        return this.head;
    }
 // Else, traverse the list to find the tail (the tail node will initially be pointing at null), and update the tail's next pointer.   
    let tail = this.head;
    while(tail.next !== null){
        tail = tail.next;
   }
   tail.next = newNode;   
  return this.head;
}