function LinkedList() { this.head = null; this.tail = null; this.length = 0; } function Node(value) { this.value = value; this.next = null; } // adds a node to the specified index // if index is specified, accepts parameter (value, index) // if no index is specified then add element to the end of list LinkedList.prototype.add = function(...value) { if (!this.head) { this.head = this.tail = new Node(...value); this.length++; return; } while (value.length) { let curr = value.pop(); this.tail.next = new Node(curr); this.tail = this.tail.next; this.length++; } } // retrieves the node at the specified index LinkedList.prototype.get = function(index) { if (index >= this.length) { return -1; } if (index === 0) { return this.head; } let previousNode = null; let currentNode = this.head; for (let i = 0; i < index; i++) { if (!currentNode.next) { break; } previousNode = currentNode; currentNode = currentNode.next; } previousNode.next = currentNode.next; this.length--; return currentNode; } // retrieves and removes the node at the specified index // if no index is specified, removes the last node (tail) LinkedList.prototype.remove = function(index) { if (this.length === 0) { return undefined; } if (this.head.value === index) { this.removeFromHead(); return this; } let previousNode = this.head; let thisNode = previousNode.next; while (thisNode) { if (thisNode.value === index) { break; } previousNode = thisNode; thisNode = thisNode.next; } if (thisNode === null) { return undefined; } previousNode.next = thisNode.next; this.length--; return this; } LinkedList.prototype.removeFromHead = function() { if (this.length === 0) { return undefined; } const value = this.head.value; this.head = this.head.next; this.length--; return value; } let linkedList = new LinkedList() linkedList.add(0); linkedList.add(1, 0); linkedList console.log(linkedList.remove().value) //should return 1 console.log(linkedList.remove().value) //should return 2