--update: find middle node of linked list

Author: ashokdey

src/_DataStructures_/LinkedList/middle-node/index.js

@@ -0,0 +1,19 @@
+function getMiddleNode(linkedList) {
+  let slow = linkedList.getFirst();
+  let fast = linkedList.getFirst();
+
+  if (!slow) {
+    return null;
+  }
+
+  while (fast.next && fast.next.next) {
+    slow = slow.next;
+    fast = fast.next.next;
+  }
+
+  return slow;
+}
+
+module.exports = {
+  getMiddleNode,
+};

src/_DataStructures_/LinkedList/middle-node/midle-node.test.js

@@ -0,0 +1,33 @@
+const { LinkedList } = require('../index');
+const { getMiddleNode } = require('.');
+
+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(getMiddleNode(list)).toEqual(null);
+  });
+
+  it('Should return `to` for the given list', () => {
+    expect(getMiddleNode(list).data).toEqual('to');
+  });
+
+  it('Should return `Welcome` after deleting 3 last nodes of the list', () => {
+    list.removeFromEnd();
+    list.removeFromEnd();
+    list.removeFromEnd();
+    expect(getMiddleNode(list).data).toEqual('Welcome');
+  });
+});