From 1666c3a0be27d18e31b8721029357b285898a1a8 Mon Sep 17 00:00:00 2001
From: BekzodIsakov <71423825+BekzodIsakov@users.noreply.github.com>
Date: Mon, 15 May 2023 13:05:09 +0500
Subject: [PATCH] fix error in SinglyLinkedList head method (#1322)

* fix error in SinglyLinkedList head method

* test: update check head test for SinglyLinkedList

* fix: code style error

* fix: remove extra semicolons

---------

Co-authored-by: Bekzod <bekzodisakov18@gmail.com>
---
 Data-Structures/Linked-List/SinglyLinkedList.js           | 4 ++--
 Data-Structures/Linked-List/test/SinglyLinkedList.test.js | 8 ++++++++
 2 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/Data-Structures/Linked-List/SinglyLinkedList.js b/Data-Structures/Linked-List/SinglyLinkedList.js
index ec0e31f5f..b093d4bde 100644
--- a/Data-Structures/Linked-List/SinglyLinkedList.js
+++ b/Data-Structures/Linked-List/SinglyLinkedList.js
@@ -40,12 +40,12 @@ class LinkedList {
 
   // Returns the head
   head () {
-    return this.headNode?.data || null
+    return this.headNode?.data ?? null
   }
 
   // Returns the tail
   tail () {
-    return this.tailNode?.data || null
+    return this.tailNode?.data ?? null
   }
 
   // Return if the list is empty
diff --git a/Data-Structures/Linked-List/test/SinglyLinkedList.test.js b/Data-Structures/Linked-List/test/SinglyLinkedList.test.js
index 543555343..53be70884 100644
--- a/Data-Structures/Linked-List/test/SinglyLinkedList.test.js
+++ b/Data-Structures/Linked-List/test/SinglyLinkedList.test.js
@@ -148,6 +148,10 @@ describe('SinglyLinkedList', () => {
 
     list.addFirst(30)
     expect(list.head()).toBe(30)
+
+    // check for a falsy head data
+    list.addFirst(false)
+    expect(list.head()).toBe(false)
   })
 
   it('Check tail', () => {
@@ -162,6 +166,10 @@ describe('SinglyLinkedList', () => {
 
     list.addFirst(30)
     expect(list.tail()).toBe(20)
+
+    // check for a falsy tail data
+    list.addLast(false)
+    expect(list.tail()).toBe(false)
   })
 
   it('Check size', () => {