app.js

//Book class : Represents a Book
class Book {
  constructor(title, author, isbn) {
    this.title = title;
    this.author = author;
    this.isbn = isbn;
  }
}
// UI class : Handles UI Tasks
class UI {
  static displayBooks() {
    const books = Store.getBooks();
    books.forEach(book => UI.addBookToList(book));
  }
  static addBookToList(book) {
    const list = document.querySelector("#book-list");

    const row = document.createElement("tr");

    row.innerHTML = `
        <td>${book.title}</td>
        <td>${book.author}</td>
        <td>${book.isbn}</td>
        <td><a href="#" class="btn btn-danger btn-sm delete">X</a></td>
        `;

    list.appendChild(row);
  }
  static deleteBook(el) {
    if (el.classList.contains("delete")) {
      el.parentElement.parentElement.remove();
    }
  }

  static showAlert(message, className) {
    const div = document.createElement("div");
    div.className = `alert alert-${className}`;
    div.appendChild(document.createTextNode(message));
    const container = document.querySelector(".container");
    const form = document.querySelector("#book-form");
    container.insertBefore(div, form);
    //  Vanish in 3 seconds
    setTimeout(() => document.querySelector(".alert").remove(), 3000);
  }

  static clearFields(row) {
    document.querySelector("#title").value = "";
    document.querySelector("#author").value = "";
    document.querySelector("#isbn").value = "";
  }
}
// Store class : Handles Storage
class Store {
  static getBooks() {
    let books;
    if (localStorage.getItem("books") === null) {
      books = [];
    } else {
      books = JSON.parse(localStorage.getItem("books"));
    }
    return books;
  }
  static addBook(book) {
    const books = Store.getBooks();

    books.push(book);
    localStorage.setItem("books", JSON.stringify(books));
  }
  static removeBook(isbn) {
    const books = Store.getBooks();

    books.forEach((book, index) => {
      if (book.isbn === isbn) {
        books.splice(index, 1);
      }
    });
    localStorage.setItem("books", JSON.stringify(books));
  }
}

// Event: Display books
document.addEventListener("DOMContentLoaded", UI.displayBooks);
// Event: Add a Book
document.querySelector("#book-form").addEventListener("submit", e => {
  // Prevent actual submit
  e.preventDefault();
  // Get Form value
  const title = document.querySelector("#title").value;
  const author = document.querySelector("#author").value;
  const isbn = document.querySelector("#isbn").value;

  //  Validate
  if (title === "" || author === "" || isbn === "") {
    UI.showAlert("Please fill in all fields", "danger");
  } else {
    //Instatiate book
    const book = new Book(title, author, isbn);

    // Add book to UI
      UI.addBookToList(book);
    //   Add book to store
      Store.addBook(book);

    // show Alert
    UI.showAlert("Book Added", "success");

    //  Clear fields
    UI.clearFields();
  }
});
// Event: Remove a Book
document.querySelector("#book-list").addEventListener("click", e => {

    // Remove book from UI
    UI.deleteBook(e.target);
    // Remove book from Store
    Store.removeBook(e.target.parentElement.previousElementSibling.textContent);
  // show Alert
  UI.showAlert("Book Removed", "success");
});