How to install ssl certificate on a port?

Question

Node.js

There is a socket server node.js (via nohup), which hangs on port 8585. The entire site was transferred to https through a certificate from let's encrypt. Therefore, the browser refused to work with http://ip:8585web sockets.
Goal: connect to node.js server at: https://domain:8585.
Question: do I need to include an ssl certificate for this port or not (and how?)? Or is it enough to enable https processing in the Node.js script itself?

Answer 1

options = {
      key: fs.readFileSync('ssl/cert.key'),
      cert: fs.readFileSync('ssl/cert.crt')
    };
    server = require('https').Server(options, express);