I am using the JSForce docs in order to create a Javascript app to connect to my Salesforce org. My code is as follows:

var jsforce = require('jsforce');
var conn = new jsforce.Connection({
    loginUrl : 'https://test.salesforce.com'
});

var username = 'my-username@domain.com';
var password = 'mypassword';


conn.login(username, password, function(err, userInfo) {
    if (err) { return console.error(err); }
    console.log(conn.accessToken);
    console.log(conn.instanceUrl);
    console.log("User ID: " + userInfo.id);
    console.log("Org ID: " + userInfo.organizationId);
  });

However, when I run it, it appears to do nothing at all. I would expact to see either the access token etc to be logged to indicate success, or an error to indicate failure. But nothing is logged at all.

When I check the login history on my Salesforce org, I can see the attempts, they are successful.

What's going on?