getDocs(booksRef)
    .then((snapshot) => {
		// console.log(snapshot.docs)
		let books = []
		snapshot.docs.forEach((doc) => {
			books.push({ ...doc.data(), id: doc.id })
		})
		console.log(books)
	})
	.catch(err => {
		console.log(err.message)
	})

getDoc(bookRef)
	.then( doc => {
		console.log(doc.data(), doc.id)
	})

const addBookForm = document.querySelector(".add")
addBookForm.addEventListener('submit', e => {
	e.preventDefault();

	// `booksRef` is query or collection
	addDoc(booksRef, {
		title: addBookForm.title.value,
		author: addBookForm.author.value,
		createdAt: serverTimestamp() // don't trust local dates
	})
	.then(() => {
		addBookForm.reset()
	})
	.catch((err) => {
		console.error(err.message)
	})
})