SAP Commerce extend standard extension javascript file

Hello

in my custom extension i use a standard module (assistedservicestorefront)

this standard extension inject assistedservicestorefront.js inside my custom extension under:

mycustomextension\web\webroot\_ui\addons\assistedservicestorefront\responsive\common\js\assistedservicestorefront.js

if i try to change this js file i lost all changes after ant build.

how i cant extend this js file in my custom extension?

thanks Angelo