This article showed you how to quickly set up an Angular form for data validation and prepare user input before sending it off to a back-end database server.
In the example, you learned how Angular uses special CSS tags to give user feedback with regard to either Angular or HTML5 input validators. To expand on this example, try validating the password fields to be the same value. You can do this in multiple ways, but try doing it in the if ($scope.formx.$valid) condition.
You can use the Plunker online editor to make sure your code is working. You can then try experimenting with some of the Angular built-in directives for checking dates and character lengths for field properties.
Finally, try writing your own custom field validator as a directive that can be placed on input fields for a form.