diff --git a/debugging/book-library/index.html b/debugging/book-library/index.html
index 23acfa71..01ac2519 100644
--- a/debugging/book-library/index.html
+++ b/debugging/book-library/index.html
@@ -1,12 +1,8 @@
 <!DOCTYPE html>
-<html>
+<html lang="en">
   <head>
-    <title> </title>
-    <meta
-      charset="utf-8"
-      name="viewport"
-      content="width=device-width, initial-scale=1.0"
-    />
+    <title>Library Books</title>
+    <meta charset="utf-8" />
     <script src="https://ajax.googleapis.com/ajax/libs/jquery/3.4.1/jquery.min.js"></script>
     <script src="https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.16.0/umd/popper.min.js"></script>
     <script src="https://maxcdn.bootstrapcdn.com/bootstrap/4.4.1/js/bootstrap.min.js"></script>
@@ -31,18 +27,20 @@ <h1>Library</h1>
       <div class="form-group">
         <label for="title">Title:</label>
         <input
-          type="title"
+          type="text"
           class="form-control"
           id="title"
           name="title"
+          placeholder="Title"
           required
         />
         <label for="author">Author: </label>
         <input
-          type="author"
+          type="text"
           class="form-control"
           id="author"
           name="author"
+          placeholder="Author"
           required
         />
         <label for="pages">Pages:</label>
@@ -51,6 +49,9 @@ <h1>Library</h1>
           class="form-control"
           id="pages"
           name="pages"
+          placeholder="Between 1 and 16000"
+          min="1"
+          max="16000"
           required
         />
         <label class="form-check-label">
diff --git a/debugging/book-library/script.js b/debugging/book-library/script.js
index 75ce6c1d..9d875e0e 100644
--- a/debugging/book-library/script.js
+++ b/debugging/book-library/script.js
@@ -1,103 +1,103 @@
-let myLibrary = [];
+const myLibrary = [];
 
-window.addEventListener("load", function (e) {
+window.addEventListener("load", function () {
   populateStorage();
-  render();
 });
 
 function populateStorage() {
-  if (myLibrary.length == 0) {
-    let book1 = new Book("Robison Crusoe", "Daniel Defoe", "252", true);
-    let book2 = new Book(
+  if (myLibrary.length === 0) {
+    const book1 = new Book("Robison Crusoe", "Daniel Defoe", "252", true);
+    const book2 = new Book(
       "The Old Man and the Sea",
       "Ernest Hemingway",
-      "127",
+      "500",
       true
     );
-    myLibrary.push(book1);
-    myLibrary.push(book2);
+    myLibrary.push(book1, book2);
+
     render();
   }
 }
 
-const title = document.getElementById("title");
-const author = document.getElementById("author");
-const pages = document.getElementById("pages");
-const check = document.getElementById("check");
-
 //check the right input from forms and if its ok -> add the new book (object in array)
 //via Book function and start render function
+
 function submit() {
+  const titleInput = document.getElementById("title").value.trim();
+  const authorInput = document.getElementById("author").value.trim();
+  const pagesInput = Number(document.getElementById("pages").value);
+  const checkInput = document.getElementById("check").checked;
   if (
-    title.value == null ||
-    title.value == "" ||
-    pages.value == null ||
-    pages.value == ""
+    titleInput == "" ||
+    pagesInput == "" ||
+    authorInput == "" ||
+    pagesInput == NaN ||
+    pagesInput < 1 ||
+    pagesInput > 16000
   ) {
     alert("Please fill all fields!");
-    return false;
   } else {
-    let book = new Book(title.value, title.value, pages.value, check.checked);
-    library.push(book);
+    let book = new Book(titleInput, authorInput, pagesInput, checkInput);
+    myLibrary.push(book);
     render();
   }
 }
 
-function Book(title, author, pages, check) {
-  this.title = title;
-  this.author = author;
-  this.pages = pages;
-  this.check = check;
+function Book(titleInput, authorInput, pagesInput, checkInput) {
+  this.title = titleInput;
+  this.author = authorInput;
+  this.pages = pagesInput;
+  this.check = checkInput;
 }
 
 function render() {
-  let table = document.getElementById("display");
-  let rowsNumber = table.rows.length;
+  const table = document.getElementById("display");
+  const rowsNumber = table.rows.length;
   //delete old table
-  for (let n = rowsNumber - 1; n > 0; n-- {
-    table.deleteRow(n);
+  while (table.rows.length > 1) {
+    table.deleteRow(1);
   }
+
   //insert updated row and cells
-  let length = myLibrary.length;
+  const length = myLibrary.length;
   for (let i = 0; i < length; i++) {
-    let row = table.insertRow(1);
-    let titleCell = row.insertCell(0);
-    let authorCell = row.insertCell(1);
-    let pagesCell = row.insertCell(2);
-    let wasReadCell = row.insertCell(3);
-    let deleteCell = row.insertCell(4);
-    titleCell.innerHTML = myLibrary[i].title;
-    authorCell.innerHTML = myLibrary[i].author;
-    pagesCell.innerHTML = myLibrary[i].pages;
+    const row = table.insertRow(1);
+    const titleCell = row.insertCell(0);
+    const authorCell = row.insertCell(1);
+    const pagesCell = row.insertCell(2);
+    const wasReadCell = row.insertCell(3);
+    const deleteCell = row.insertCell(4);
+    titleCell.textContent = myLibrary[i].title;
+    authorCell.textContent = myLibrary[i].author;
+    pagesCell.textContent = myLibrary[i].pages;
 
     //add and wait for action for read/unread button
-    let changeBut = document.createElement("button");
-    changeBut.id = i;
-    changeBut.className = "btn btn-success";
-    wasReadCell.appendChild(changeBut);
+    const changeButton = document.createElement("button");
+
+    changeButton.className = "btn btn-success";
+    wasReadCell.appendChild(changeButton);
     let readStatus = "";
-    if (myLibrary[i].check == false) {
-      readStatus = "Yes";
-    } else {
-      readStatus = "No";
-    }
-    changeBut.innerText = readStatus;
 
-    changeBut.addEventListener("click", function () {
+    myLibrary[i].check ? (readStatus = "Yes") : (readStatus = "No");
+
+    changeButton.innerText = readStatus;
+
+    changeButton.addEventListener("click", function () {
       myLibrary[i].check = !myLibrary[i].check;
+
       render();
     });
-
     //add delete button to every row and render again
-    let delButton = document.createElement("button");
-    delBut.id = i + 5;
-    deleteCell.appendChild(delBut);
-    delBut.className = "btn btn-warning";
-    delBut.innerHTML = "Delete";
-    delBut.addEventListener("clicks", function () {
-      alert(`You've deleted title: ${myLibrary[i].title}`);
+    const button = document.createElement("button");
+    deleteCell.appendChild(button);
+    button.className = "btn btn-warning";
+    button.textContent = "Delete";
+    button.addEventListener("click", function () {
+      const deletedBook = myLibrary[i].title;
       myLibrary.splice(i, 1);
+
       render();
+      alert(`You've deleted title: ${deletedBook}`);
     });
   }
 }
