If you ever took part in any serious JS development in general and AngularJS specifically, you know that every time you create a new js file, you need to manually include a reference to it in the index.html file, other wise it won’t be included and the app will fail.
How would you feel about not having to do that?
When working on large scale projects, java back-end code is usually being built using Apache Maven.
This is usually part of a larger framework in charge of project life cycle that is part of the Continuous Integration DevOps realm, either Hudson, Jenkins or something else.
In such a case, you’d want your AngularJS code to run grunt/gulp as part of the CI procedure as well.
A JS Black Belt Blog 