Query Chaining

// ========== THIS IS MY AUTHOR SCHEMA ============
authorSchema = new mongoose.Schema({
    name: {
        type: String,
        required: true
    },
    books: [{
        type: mongoose.Schema.Types.ObjectId,
        ref: 'Book'
    }],
});

// ========= THIS IS MY BOOK SCHEMA =========
const bookSchema = new mongoose.Schema({
    title: {
        required: true,
        type: String
    },
    authors: [{
        id: {
            type: mongoose.Schema.Types.ObjectId,
            ref: 'Author'
        },
        name: String
    }],
    identifiers: [],
    publisher: String,
    publishedDate: Date,
    description: String,
    textSnippet: String,
    imageURL: String,
    categories: [],
});

// ====== THIS IS HOW I CURRENTLY GET ALL THE BOOKS (THIS IS WHERE I WANT TO FILTER THE RESULT TO MATCH OTHER SEARCHES) ==========

db.Author.find({'name': authorSearch})
                .populate('books')
                .limit(limit)
                .skip(limit * page)
                .then(function(authors){
                    if(authors.length > 0){
                        const books = [];
                        authors.forEach(function(author){
                            books.push(...author.books);
                        });
                        return books;
                    }
                });