NRelay Help

Today I decided to get into NRelay and try it out. Thing is, I didn't seem to understand how to write to the socket. I tried looking a bit around but didn't find much. Could anyone help me?

Found a solution for my original issue. Although, another thing I don't understand. Why is there a "hello-plugin.js" and "hello-plugin.ts"? I read a bit about .ts and I don't understand what's it's purpose.