Magento 2 purposes the requireJS library, i.e., javascript document loader, to work with JS records. The designers may, nonetheless, expect to involve custom Javascript for extra elements not presented by the default Magento 2.
For instance, a custom module requires functionalities, for example, to choose a picture, crop a picture, show graphs, and so on. There are many highlights that can be executed utilizing Javascript and further develop the Magento 2 administrator board.
Learn add custom JS file in Magento 2 admin panel at:https://meetanshi.com/blog/add-custom-js-file-in-magento-2-admin-panel/