test passed

solution.js

@@ -1,5 +1,159 @@
 const { nums, words } = require("./data/data.js");
 
+class Node{
+  constructor(data){
+    this.data = data
+    this.next = null
+  }
+}
+
+class LinkedList{
+  constructor(head = null, tail = null, length = 0){
+    this.head = head
+    this.tail = tail
+    this.length = length
+
+  }
+
+  //methods
+  insert(data){
+  let newNode = new Node(data)
+  newNode.next = this.head;
+  this.head = newNode
+  }
+
+  size(){
+    let count = 0
+    let currentNode = this.head;
+    while (currentNode){
+      count++;
+      //how to iterate or traverse to the next
+      currentNode = currentNode.next
+    }
+    return count
+  }
+
+  //by key
+  delete(key){
+    let currentNode = this.head;
+    let count = 0;
+    while (count < key - 1) {
+      currentNode = currentNode.next;
+      count++;
+    }
+    //to skip over/pop
+    currentNode.next = currentNode.next.next;
+  } 
+
+
+  //element
+  getFirst(){
+    return this.head
+  }
+
+
+  //emelent
+  getLast(){
+    let currentNode = this.head 
+    while (currentNode.next != null) {
+        currentNode = currentNode.next
+    }
+    return currentNode
+
+  }
+
+
+  // an element by key and return data
+  search(data){
+    let currentNode = this.head
+    while(currentNode != null){
+      if(currentNode.data === data){
+        return currentNode
+      }
+      currentNode = currentNode.next
+    }
+    return null
+  } 
+
+
+  //retrieve kth element
+  getKth(k){
+let currentNode = this.head
+let count = 0
+while(currentNode < k){
+  count++
+  currentNode = currentNode.next
+}
+return currentNode
+  } 
+
+
+  //retrieve kth from last element
+  getKthToLast(k){
+    let currentNode = this.head;
+    let size = this.size();
+
+    while (size - 1 > k) {
+      // console.log(currentNode);
+      currentNode = currentNode.next;
+      size--;
+    };
+    return currentNode;
+  }
+
+
+  //check if list is empty
+
+  isEmpty(){
+//  if (this.head){
+//   return false
+//  } else {
+//   return true
+//  }
+//or
+if (this.size() == 0){
+  return true
+} else {
+  return false
+}
+  }
+
+
+  //the linked list
+  clear(){
+    this.head = null
+  }
+
+  //convert data from linked list to an array
+  toArray(){
+let currentNode = this.head
+this.array = []
+while (currentNode) {
+  this.array.push(currentNode.data)
+  currentNode = currentNode.next
+}
+return this.array
+  }
+
+
+  //check for duplicates - return true if contains duplicates, false if not
+  containsDuplicates(data){
+let currentNode = this.head
+let array = []
+while(currentNode){
+  if(array.includes(currentNode.data)){
+
+    return true
+  } else {
+array.push(currentNode.data)
+currentNode = currentNode.next
+} 
+}
+return false
+}
+
+}
+
 module.exports = {
   Node,
   LinkedList,