ES6 unshift() 数组方法

var myBook = new book("Perl", "Mohtashim");
book.prototype.price = null;
myBook.price = 100;

console.log("Book title is : " + myBook.title + "<br>");
console.log("Book author is : " + myBook.author + "<br>");
console.log("Book price is : " + myBook.price + "<br>");