Controllers

AngularJS completes the MVC framework through the implementation of controllers. Controllers augment the scope by setting up the initial state or values in the scope and by adding behavior to the scope. For example, you can add a function that sums values in a scope to provide a total such that if the model data behind the scope changes, the total value always changes.

You add controllers to HTML elements by using a directive and then implement them as JavaScript code in the background.