-
+
diff --git a/debugging/book-library/script.js b/debugging/book-library/script.js
index 75ce6c1d..881ee634 100644
--- a/debugging/book-library/script.js
+++ b/debugging/book-library/script.js
@@ -1,103 +1,142 @@
-let myLibrary = [];
+// const is safer than let here because myLibrary is never reassigned —
+// we only call .push() and .splice() on it, which modify its contents, not the variable itself
+const myLibrary = [];
-window.addEventListener("load", function (e) {
- populateStorage();
+// Declare all shared DOM references at the top of the file
+// These are const because they always point to the same HTML elements
+const titleInput = document.getElementById("title");
+const authorInput = document.getElementById("author");
+const pagesInput = document.getElementById("pages");
+const readCheckbox = document.getElementById("check");
+
+// Wait for the page to fully load before running any code
+window.addEventListener("load", function () {
+ addDefaultBooks();
render();
});
-function populateStorage() {
- if (myLibrary.length == 0) {
- let book1 = new Book("Robison Crusoe", "Daniel Defoe", "252", true);
- let book2 = new Book(
- "The Old Man and the Sea",
- "Ernest Hemingway",
- "127",
- true
+// Add two default books so the page is not empty on first load
+function addDefaultBooks() {
+ if (myLibrary.length === 0) {
+ // Page count is stored as a NUMBER (252, not "252") — correct data type
+ myLibrary.push(new Book("Robinson Crusoe", "Daniel Defoe", 252, true));
+ myLibrary.push(
+ new Book("The Old Man and the Sea", "Ernest Hemingway", 127, true)
);
- myLibrary.push(book1);
- myLibrary.push(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() {
- if (
- title.value == null ||
- title.value == "" ||
- pages.value == null ||
- pages.value == ""
- ) {
- alert("Please fill all fields!");
- return false;
- } else {
- let book = new Book(title.value, title.value, pages.value, check.checked);
- library.push(book);
- render();
- }
-}
-
-function Book(title, author, pages, check) {
+// Book is a constructor function — a template for creating book objects
+function Book(title, author, pages, hasBeenRead) {
this.title = title;
this.author = author;
this.pages = pages;
- this.check = check;
+ this.hasBeenRead = hasBeenRead;
}
-function render() {
- let table = document.getElementById("display");
- let rowsNumber = table.rows.length;
- //delete old table
- for (let n = rowsNumber - 1; n > 0; n-- {
- table.deleteRow(n);
+// sanitiseText trims leading and trailing spaces from a string
+// Prevents accepting inputs that contain only spaces as valid values
+function sanitiseText(value) {
+ return value.trim();
+}
+
+// sanitisePages converts the pages input to a safe integer
+// Rejects scientific notation like "3e2" which would display strangely
+function sanitisePages(value) {
+ const trimmed = value.trim();
+ // If the input contains "e" or "E", it is scientific notation — reject it
+ if (trimmed.toLowerCase().includes("e")) {
+ return NaN;
}
- //insert updated row and cells
- let 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;
-
- //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);
- let readStatus = "";
- if (myLibrary[i].check == false) {
- readStatus = "Yes";
- } else {
- readStatus = "No";
- }
- changeBut.innerText = readStatus;
-
- changeBut.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: ${myLibrary[i].title}`);
- myLibrary.splice(i, 1);
- render();
- });
+ const parsed = Number(trimmed);
+ if (trimmed === "" || isNaN(parsed) || parsed <= 0) {
+ return NaN;
+ }
+ return Math.floor(parsed);
+}
+
+// Called when the user clicks Submit
+function addBook() {
+ // Step 1: Sanitise the inputs — clean them before checking or using them
+ const cleanTitle = sanitiseText(titleInput.value);
+ const cleanAuthor = sanitiseText(authorInput.value);
+ const cleanPages = sanitisePages(pagesInput.value);
+
+ // Step 2: Validate — reject empty strings and invalid page numbers
+ if (cleanTitle === "" || cleanAuthor === "" || isNaN(cleanPages)) {
+ alert("Please fill all fields with valid values!");
+ return;
+ }
+
+ // Step 3: Create and store the new book using the cleaned values
+ const newBook = new Book(
+ cleanTitle,
+ cleanAuthor,
+ cleanPages,
+ readCheckbox.checked
+ );
+ myLibrary.push(newBook);
+
+ // Step 4: Clear the form fields after adding the book
+ titleInput.value = "";
+ authorInput.value = "";
+ pagesInput.value = "";
+ readCheckbox.checked = false;
+
+ render();
+}
+
+// createReadButton builds and returns a toggle button for a single book
+function createReadButton(index) {
+ const button = document.createElement("button");
+ button.className = "btn btn-success";
+ button.textContent = myLibrary[index].hasBeenRead ? "Yes" : "No";
+
+ button.addEventListener("click", function () {
+ myLibrary[index].hasBeenRead = !myLibrary[index].hasBeenRead;
+ render();
+ });
+
+ return button;
+}
+
+// createDeleteButton builds and returns a delete button for a single book
+function createDeleteButton(index) {
+ const button = document.createElement("button");
+ button.className = "btn btn-warning";
+ button.textContent = "Delete";
+
+ button.addEventListener("click", function () {
+ // Show an alert with the deleted book's title — restoring original behaviour
+ alert(`"${myLibrary[index].title}" has been deleted.`);
+ myLibrary.splice(index, 1);
+ render();
+ });
+
+ return button;
+}
+
+// render() redraws the entire table from the current myLibrary array
+function render() {
+ const table = document.getElementById("display");
+
+ // Clear the tbody in one step — simpler and faster than deleting rows one by one
+ const tbody = table.querySelector("tbody");
+ tbody.innerHTML = "";
+
+ for (let i = 0; i < myLibrary.length; i++) {
+ const row = tbody.insertRow();
+ const titleCell = row.insertCell(0);
+ const authorCell = row.insertCell(1);
+ const pagesCell = row.insertCell(2);
+ const readCell = row.insertCell(3);
+ const deleteCell = row.insertCell(4);
+
+ titleCell.textContent = myLibrary[i].title;
+ authorCell.textContent = myLibrary[i].author;
+ pagesCell.textContent = myLibrary[i].pages;
+
+ readCell.appendChild(createReadButton(i));
+ deleteCell.appendChild(createDeleteButton(i));
}
}