diff --git a/script.js b/script.js
index c7c6805..048fcff 100644
--- a/script.js
+++ b/script.js
@@ -6,15 +6,15 @@
  *
  */
 
- // select elements & assign them to variables
- let newTask = document.querySelector('#new-task');
- let form = document.querySelector('form');
- let todoUl = document.querySelector('#items');
- let completeUl = document.querySelector('.complete-list ul');
+// select elements & assign them to variables
+let newTask = document.querySelector('#new-task');
+let form = document.querySelector('form');
+let todoUl = document.querySelector('#items');
+let completeUl = document.querySelector('.complete-list ul');
 
 
 // functions
-let createTask = function(task) {
+let createTask = function (task) {
     let listItem = document.createElement('li');
     let checkBox = document.createElement('input');
     let label = document.createElement('label');
@@ -28,16 +28,22 @@ let createTask = function(task) {
     return listItem;
 }
 
-let addTask = function(event) {
+let addTask = function (event) {
     event.preventDefault();
-    let listItem = createTask(newTask.value);
-    todoUl.appendChild(listItem);
-    newTask.value = "";
-    // bind the new list item to the incomplete list
-    bindInCompleteItems(listItem, completeTask);
+
+    if (newTask.value.trim() !== "") {
+        let listItem = createTask(newTask.value);
+        todoUl.appendChild(listItem);
+        newTask.value = "";
+        // bind the new list item to the incomplete list
+        bindInCompleteItems(listItem, completeTask);
+    } else {
+        window.alert("Please write a valid task!");
+    }
+
 }
 
-let completeTask = function() {
+let completeTask = function () {
     let listItem = this.parentNode;
     let deleteBtn = document.createElement('button');
     deleteBtn.innerText = 'Delete';
@@ -50,27 +56,27 @@ let completeTask = function() {
     bindCompleteItems(listItem, deleteTask);
 }
 
-let deleteTask = function() {
+let deleteTask = function () {
     let listItem = this.parentNode;
     let ul = listItem.parentNode;
     ul.removeChild(listItem);
 }
 
-let bindInCompleteItems = function(taskItem, checkboxClick) {
+let bindInCompleteItems = function (taskItem, checkboxClick) {
     let checkBox = taskItem.querySelector('input[type="checkbox"]');
     checkBox.onchange = checkboxClick;
 }
 
-let bindCompleteItems = function(taskItem, deleteButtonClick) {
+let bindCompleteItems = function (taskItem, deleteButtonClick) {
     let deleteButton = taskItem.querySelector('.delete');
     deleteButton.onclick = deleteButtonClick;
 }
 
-for(let i=0; i< todoUl.children.length; i++ ) {
+for (let i = 0; i < todoUl.children.length; i++) {
     bindInCompleteItems(todoUl.children[i], completeTask);
 }
 
-for(let i=0; i< completeUl.children.length; i++ ) {
+for (let i = 0; i < completeUl.children.length; i++) {
     bindCompleteItems(completeUl.children[i], deleteTask);
 }