how to list and connect with devices connected to the same wifi using webRTC in node , is it need some external libraries?

I learned java core and OOP. I aim to become a web developer. However, I still consider myself new in programming. I read somehow that Node js is faster and better than java in some cases. How can I choose whether I continue in Java or learn node js?

i have a backend written in nodejs and frontend in react. Now suppose if i have a button in frontend and when i click it i want to execute a java code, which is a .jar file and that file is saved at my backend, now my question is if i deploy this backend to netlify server, the java code does not run, so is it because that netlify server do not have jdk to run my java code ??

i have a backend written in nodejs and frontend in react. Now suppose if i have a button in frontend and when i click it i want to execute a java code, which is a .jar file and that file is saved at my backend, now my question is if i deploy this backend to netlify server, the java code does not run and i get error, so is this error because that netlify server do not have jdk to run my java code ??