Customer Specific Javascript code implementation in UI5 Views/Controllers?

How to handle the enhancements using JavaScript code in UI5 view/controllers as like in ABAP. In ABAP, we have a feasibiilty of customer code is not getting overwritten for every release/upgrade by using enhancement concept(like BADI's...).

So, do we have any kind of such feasibility avaiable in UI5 too using JavaScript.