JS app refreshing on button submit, cannot figure out why

I am learning JS and have a page done in vanilla JS and HTML and for the life of me cannot figure out why when I hit submit, the page refreshes. Please help! I have double checked the ID for the form that I have the event listener on and it is correct.

// Book Constructor
function Book(title, author, isbn) {
  this.title = title;
  this.author = author;
  this.isbn = isbn;
}

// UI Constructor
function UI() {}

// Event Listeners
document.getElementById('book-form').addEventListener('submit', function(e){
  const title = document.getElementById('title').value,
        author = document.getElementById('author').value,
        isbn = document.getElementById('isbn').value

  
  console.log(title, author, isbn);
  e.preventDefault();
});