ES6 - Prototype


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The prototype property allows you to add properties and methods to any object (Number, Boolean, String and Date, etc.).

Note − Prototype is a global property which is available with almost all the objects.

Use the following syntax to create a Boolean prototype.

object.prototype.name = value

Example

The following example shows how to use the prototype property to add a property to an object.

<html>
   <head>
      <title>User-defined objects</title>
      <script type="text/javascript">
         function book(title, author){
            this.title = title;
            this.author = author;
         }
      </script>
   </head>
   <body>
      <script type="text/javascript">
         var myBook = new book("Perl", "Tom");
         book.prototype.price = null;
         myBook.price = 100;
         document.write("Book title is : " + myBook.title + "<br>");
         document.write("Book author is : " + myBook.author + "<br>");
         document.write("Book price is : " + myBook.price + "<br>");
      </script>
   </body>
</html>

The following output is displayed on successful execution of the above code.

Book title is : Perl
Book author is : Tom
Book price is : 100
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