script2.js

console.log('sssss')

class Node {

	constructor(val) {
		this.val = val
		this.prev = null
		this.next = null
	}
}

class DoublyLinkedList {

	constructor() {
		this.head = null
		this.tail = null
		this.length = 0
	}

	push(val) {
		let node = new Node(val)
		if (!this.head) {
			this.head = node
			this.tail = node
		} else {

			let temp = this.tail
			this.tail = node
			node.prev = temp
			temp.next = node
		}
		this.length++
		return this
	}

	pop() {
		if (!this.head) return undefined
		let temp = this.tail

		if (this.length === 1) {
			this.head = null
			this.tail = null
		}
		else {
			this.tail = temp.prev
			this.tail.next = null
			temp.prev = null
		}
		this.length--
		return this
	}

	unshift(val) {
		let node = new Node(val)
		if (!this.head) {
			this.head = node
			this.tail = node
		} else {
			let temp = this.head
			this.head = node
			node.next = temp
			temp.prev = node
		}
		this.length++
		return this

	}

	shift() {
		if (!this.head) return undefined

		let temp = this.head
		if (this.length === 1) {
			this.head = null
			this.tail = null			
		} else {
			this.head = temp.next
			this.head.prev = null
			temp.next = null
		}
		this.length--
		return this	

	}

	insert(index, value) {
		if (index < 0 || index > this.length) return false
		let node = new Node(value)
		if (index === 0) return !!this.unshift(value)
		if (index === this.length) return !!this.push(value)

		let current = this.head
		let counter = 0

		while(counter !== index) {
			current = current.next
			counter++
		}
		let temp = current
		let prev = temp.prev
		prev.next = node
		node.next = temp
		node.prev = prev

		temp.prev = node
		this.length++
		return true	
	}

	remove(index) {

		if (index < 0 || index > this.length-1) return false
		if (index === 0) return !!this.shift()
		if (index === this.length-1) return !!this.pop()

		let current = this.head
		let counter = 0

		while(counter !== index) {
			current = current.next
			counter++
		}

		let prev = current.prev
		let next = current.next

		prev.next = next
		next.prev = prev
		this.length--
		return true

	}

	reverse() {
		if (!this.head) return undefined
		let node = this.head
		this.head = this.tail
		this.tail = node

		let counter = 0
		let prev = null
		let next

		while(counter < this.length) {
			next = node.next
			node.prev = next
			node.next = prev

			prev = node
			node = next
			counter++
		}
		return this

	} 

}

let list = new DoublyLinkedList

list.push(1)
list.push(2)
list.push(3)
list.push(4)

// list.pop()

// list.unshift(0)
// list.shift()
// list.insert(5,"zedi")
// list.remove(1)

console.log(list)