just how?

class book
             {
                 constructor(_name = "",_year = 0)
                 {
                  this.name = _name;
                  this.year = _year;
                 }

                 getname = function()
                 {
                     return this.name;
                 }

                 getyear = function()
                 {
                     return this.year;
                 }

                 getallinfo = function()
                 {
                     var allinfo = "Book Info: \n Name: " + this.name + "\n Year: " + this.year + "\n";
                 }

                 setname = function(_name)
                 {
                     this.name = _name;
                 }

                 setyear = function(_year)
                 {
                     this.year = _year;
                 }

             }
             class author
             {
                 constructor(_name = "",_yearofbirth = 0,_books = [])
                 {
                     this.name = _name;
                     this.yearofbirth = _yearofbirth;
                     this.books = _books;
                 }

                 getname = function ()
                 {
                     return this.name;
                 }

                 getyearofbirth = function()
                 {
                     return this.yearofbirth;
                 }

                 getbooks = function()
                 {
                     for(i =0; i< books.length;i++)
                     {
                        books[i].getallinfo();
                     }
                 }

                 getallinfo = function()
                 {
                     let fullinfo = "Author Info: \n Name: " + this.getname() + "\n Birth Year: " + this.getyearofbirth() + "\n Books by this author: " + this.getbooks() + "\n";
                     return fullinfo;
                 }

                 setname = function(_name)
                 {
                     this.name = _name;
                 }

                 setyearofbirth = function(_yearofbirth)
                 {
                     this.yearofbirth = _yearofbirth;
                 }

                 setbooks = function(_books)
                 {
                     this.books = _books;
                 }

                 addbook = function(_book)
                 {
                     this.books.push(book);
                 }

                 removebook = function(_book)
                 {
                     for(book in books)
                     {
                         if(book === _book)
                         {
                             this.books.splice(books.indexOf(book),1);
                         }
                     }
                 }

             }