Singly-linked list example implementation in Java Script

Let’s store these values from the diagram above in linked list.

Using Object:

const list = {
    head: {
        value: 20,
        next: {
            value: 18,
            next: {
                value: 15,
                next: {
                    value: 67,
                    next: null
                }
            }
        }
    }
};


/* example of retrieving the value at second position */

console.log(list.head.next); // the result should be 18

Using class

function ListNode(val) {
    this.val = val;
    this.next = null;
}

var linkList = new ListNode(20);
linkList.next = new ListNode(18);
linkList.next.next = new ListNode(15);
linkList.next.next.next = new ListNode(67);
linkList.next.next.next.next = null;

/* example of retrieving the last value */
console.log(linkList.next.next.next); // the result should be 67

Traversing double linked list example

var list  = {
  one: {value: 1, prev: null, next: null},
  two: {value: 2, prev: null, next: null},
  three: {value: 3, prev: null, next: null}
}

var root = list.one;

list.one.next = list.two;
list.two.prev = list.one;
list.two.next = list.three;
list.three.prev = list.two;

var i = 0;

var element = root;
var loop = true;

while(loop == true) {
  console.log(">>", element.value);
  if(element.next == null)
      loop = false;
  element = element.next;
}