Doubly Linked List

doublyLinkedList.js

class LinkedList {
    constructor() {
        this.head = null;
        this.tail = null;
    }
    createElement(value, next, prev) {
        return { value, next, prev }
    }
    addToHead(value) {
        let node = this.createElement(value,null ,this.head)
        this.head && (this.head.next = node);
        !this.tail && (this.tail = node);

        this.head = node;
        
        return this;
    }
    addToTail(value) {
        let node = this.createElement(value, this.tail, null);
        (this.tail) && (this.tail.prev = node);
        this.tail = node; 
        return this;
    }
    getMidItem() {
        let p1,p2;
        p1=p2=this.tail;

        while(p2.next && p2.next.next) {
            p1 = p1.next;
            p2 = p2.next.next;
        }
        return p1; 
    }   
    *[Symbol.iterator](){
       let element = this.tail;
      while(element) {
         yield element.value; 
        element = element.next;
       } 
    }
}
let list = new LinkedList();
list.addToHead(2).addToHead(3).addToHead(4).addToHead(5).addToTail(1);
window.list = list;

console.log('head of List: ', list.head)
console.log('iterate List', [...list])
console.log('getMidItem', list.getMidItem())