data books

const STORAGE_KEY = "BOOK_APPS";

let books = [];

function isStorageExist() /* boolean */  {
   if(typeof(Storage) === undefined){
       alert("Browser kamu tidak mendukung local storage");
       return false
   }
   return true;
}
function saveData() {
   const parsed = JSON.stringify(books);
   localStorage.setItem(STORAGE_KEY, parsed);
   document.dispatchEvent(new Event("ondatasaved"));
}

function loadDataFromStorage() {
   const serializedData = localStorage.getItem(STORAGE_KEY);

   let data = JSON.parse(serializedData);

   if(data !== null)
       books = data;

   document.dispatchEvent(new Event("ondataloaded"));
}

function updateDataToStorage() {
   if(isStorageExist())
       saveData();
}

function composeBookObject(title, author, year, isCompleted) {
   return {
       id: +new Date(),
       title,
       author,
       year,
       isCompleted
   };
}

function findBook(bookId) {
   for(book of books){
       if(book.id === bookId)
           return book;
   }
   return null;
}


function findBookIndex(bookId) {
   let index = 0
   for (book of books) {
       if(book.id === bookId)
           return index;

       index++;
   }

   return -1;
}
 function refreshDataFromBooks() {
    const listUncompleted = document.getElementById(UNCOMPLETED_LIST_BOOK_ID);
    let listCompleted = document.getElementById(COMPLETED_LIST_BOOK_ID);


    for(book of books){
        const newBook = makeBook(book.title, book.author, book.year, book.isCompleted);
        newBook[BOOK_ITEMID] = book.id;


        if(book.isCompleted){
            listCompleted.append(newBook);
        } else {
            listUncompleted.append(newBook);
        }
    }
 }