done

[SheikhaAlenezi]

No description provided.

[shereengh]

function addSecondAuthor(book: Book, additionalAuthor: string): Book {
// write your code here...
if (Array.isArray(book.author)) {
return {
...book,
author: [...book.author, additionalAuthor],
};
} else {
return {
...book,
author: [book.author, additionalAuthor],
};
}
}

No need to check if its array if you're applying the same code for both cases