Learn TypeScript 3 by Building Web Applications

Implementing the clearNewBookForm method

This method is very straightforward. We retrieve the form element from the DOM and call reset() on it:

clearNewBookForm(collectionIdentifier: string): void { 
    if (!collectionIdentifier) { 
        throw new Error("The collection identifier must be          provided!"); 
    } 
 
    const newBookForm = document.getElementById    (`newBook-${collectionIdentifier}`) as HTMLFormElement; 
 
    if (!newBookForm) { 
        throw new Error(`Could not find the new book form for         collection ${collectionIdentifier}`); 
    } 
 
    newBookForm.reset(); 
}

Let's continue with the removeBook method.