Things to notice

Take a look through the source and note:

The script tag that bootstraps the Angular environment.
The text input form control which is bound to the greeting name text.
There is no need for listener registration and event firing on change events.
The implicit presence of the name variable which is in the root scope.
The double curly brace {{markup}}, which binds the name variable to the greeting text.
The concept of data binding, which reflects any changes to the input field in the greeting text.