From 048c8361b74982e4c866cbafd63930bd0a9193b4 Mon Sep 17 00:00:00 2001
From: Lokesh Jadhav <lokesh.jadhav10@gmail.com>
Date: Sun, 14 Jan 2018 11:35:00 +0100
Subject: [PATCH] Add a queue empty check in dequeue function

---
 data-structures/queue.js | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/data-structures/queue.js b/data-structures/queue.js
index 52d9464..4785377 100644
--- a/data-structures/queue.js
+++ b/data-structures/queue.js
@@ -68,6 +68,9 @@ Queue.prototype.enqueue = function(value) {
 
 // O(1)
 Queue.prototype.dequeue = function() {
+  if (this.count() === 0) {
+     return 'Queue is empty! Enqueue an element before you dequeue';
+  }
   var element = this._storage[this._head];
   delete this._storage[this._head];
   if (this._head < this._tail) this._head++;