We’ve released an issue background script module for the new Jira issue view. This module lets your app add an invisible panel to the issue view to listen for events, poll for changes, or run code that consumes the JavaScript API. As a result, your app can now execute its required functionality without adding unnecessary UI elements.
To start using the new issue background script module, take a look at the issue background script documentation. For even more locations in the new issue view, check out new issue view locations.