Custom Javascript for Specific Block or Row

if I want to give custom functionality to specific row content only or I want to target a specific class within the row I need to go theme and then add my javascript what if we can come over from his hustle and add an option or block to custom javascript in it. This is much needed option. I know in pro version I can add custom script in page or post but I want it in specific Block maybe some one else needed this too.