8. Give Javascript to define a class Book.   
Data members: title, author, numStars . 
Methods: toString(), getAuthor(), setAuthor. 



//  not debugged, possible syntax errors
 function Book (author, title, numStars) {
  	this.author = author;
  	this.title = title;
  	this.numStars = numStars;
  	this.toString = bookToString;
  	this.getAuthor = bookGetAuthor;
  	this.setAuthor = bookSetAuthor;
  	}
  	
 function bookToString() {
    s = "";
    s += this.author + " " + this.title;
    return s;
    }
    
 function bookGetAuthor() {
    return this.author;
    }
    
 function bookSetAuthor(author) {
    this.author = author;
    }