Simple-service-tunneling.js

const { createTunnel, closeTunnel } = require('proxy-chain');

// This is how connection strings usually look like
const serviceConnectionString = '<protocol>://<auth>@<service-hostname>:<service port>';

// Create tunnel for the service, this call will start local tunnel and 
// return string in format localhost:<selected-free-port> which is address
// of the local tunnel.
const tunnelInfo = await createTunnel(
  'http://<username>:<password>@<proxy-server-hostname>:<proxy-server-port>',
  '<service-hostname>:<service-port>'
);

// We will reformat the connection string to use the tunnel instead of real hostname
const tunneledServiceConnectionString = serviceConnectionString.replace('<service-hostname>:<service-port>', tunnelInfo);

// Connect to any kind of client that uses connection strings
client.connect(tunneledServiceConnectionString);

// do something with the client...

// Close the tunnel when we are done
closeTunnel(tunnelInfo);