--update: find element from last of the linked list

Author: ashokdey

src/_DataStructures_/LinkedList/element-from-last/element-from-last.test.js

@@ -0,0 +1,30 @@
+const { getElementFromlast } = require('.');
+const { LinkedList } = require('../index');
+
+describe('Find the middle node of a LinkedList', () => {
+  let list = null;
+  beforeEach(() => {
+    list = new LinkedList();
+    list.addAtBeginning('Hello');
+    list.addAtEnd('World!');
+    list.addAtEnd('Welcome');
+    list.addAtEnd('to');
+    list.addAtEnd('the');
+    list.addAtEnd('world');
+    list.addAtEnd('of');
+    list.addAtEnd('JavaScript');
+  });
+
+  it('Should return `null` for empty list', () => {
+    list.delete();
+    expect(getElementFromlast(list, 10)).toEqual(null);
+  });
+
+  it('Should return `world` as 3rd from last of the list', () => {
+    expect(getElementFromlast(list, 3).data).toEqual('world');
+  });
+
+  it('Should return `Welcome` as 6th from last of the list', () => {
+    expect(getElementFromlast(list, 6).data).toEqual('Welcome');
+  });
+});

src/_DataStructures_/LinkedList/element-from-last/index.js

@@ -0,0 +1,22 @@
+function getElementFromlast(linkedList, index) {
+  let normal = linkedList.getFirst();
+  let nth = linkedList.getFirst();
+  let count = 0;
+
+  if (!normal) {
+    return null;
+  }
+
+  while (normal) {
+    if (count >= index) {
+      nth = nth.next;
+    }
+    normal = normal.next;
+    count += 1;
+  }
+  return nth;
+}
+
+module.exports = {
+  getElementFromlast,
+};