It is for sure, a tendency. You will still hear a lot about unit tests and TDD.
You want to be sure your new changes have not broken down any other thing you knew was working? So, unit tests is your answer.
Some advantages:
Yes, you will find out there many others libraries to implement unit tests in your code, and some for your Javascript, too.
Why, then, to use jfUnit?
You can simulate the use of your system, such as navigating through menus, filling forms or clicking on buttons.
You can also apply a delay, to watch the steps being executed one by one.