Adding external .js files to a new Rails 6 web app

I have created a new rails 6 app. in rails 6, javascript folder is outside assets. I have copied all the css and js files from an existing application to this new one and application.css,application.js are updated. application.css working fine but application.js is not working. while compiling(bin/webpack) webpack it is showing error like this => ERROR in ./app/javascript/packs/application.js
Module not found: Error: Can't resolve 'file_name' in '/home/app/javascript/packs'
@ ./app/javascript/packs/application.js
in application.js i have added those .js files with require('file_name') syntax. and i pasted all the .js files on 'app/javascript/packs' folder. please help me to solve this issue.

I have created src folder inside app/javascript folder and pasted all .js files into it. application.js also done by require('src/file_name'), and then I changed webpacker.yml resolved_paths to resolved_paths: ['app/javascript/src'] . Now it is working fine.