When JavaScript doesn't provide the method you need you can add it yourself.

In the last few modern JavaScript tutorials we have looked at the many different objects that JavaScript defines for us to use with our JavaScript code. We are not just limited to those methods that JavaScript provides for those objects though because JavaScript allows us to extend the functionality of any object at any time simply by defining additional methods of our own. In the twentieth modern JavaScript tutorial we look at how you can extend the functioning of the built-in objects. This tutorial includes six examples of how to extend date objects and one of how to extend string objects.

Extending Objects