Problem: Your code base probably contains a lot of copy/pasted code, but...
Problem: Your code base probably contains a lot of copy/pasted code, but it's hard to find.
Solution: jscpd
jscpd is a command line tool that finds copy/pasted code and reports specific duplicated lines.
Works for over 150 languages.
Example report:
Link: https://github.com/kucherenko/jscpd