No Access-Control-Allow-Origin header is present message on bulk API response via Visualforce page

I have a Visualforce page that I am using to bulk upload records from a csv file. In using the JSforce framework, I am creating my connection like this:

var conn = new jsforce.Connection({ 
                    accessToken: '{!$Api.Session_Id}',
                    serverUrl: 'https://cs7.salesforce.com',
                    proxyUrl: '/services/proxy'
                });

This org also has the My Domain option configured, and I have tried setting the serverUrl with the custom domain name as well. I am able to create a job, and batches, and execute them, but when the “onresponse” event fires, I start getting this error message:

XMLHttpRequest cannot load https://mydomain--demo.cs7.my.salesforce.com/_ui/common/request/servlet/JsLoggingServlet. No ‘Access-Control-Allow-Origin’ header is present on the requested resource. Origin ‘https://mydomain--demo--c.cs7.visual.force.com’ is therefore not allowed access.

In my current codebase, I am creating the job manually:

var job = conn.bulk.createJob('SMBulk__c','insert');

And adding the batches to that job:

var batch = job.createBatch();
batch.execute(subfile);

I have also tried this using the bulk load method as well:

conn.bulk.load("SMBulk__c","insert",subfile,
                                     function(err,rets){});

Any help or advice would be greatly appreciated!! Jim

[stomita]

I was wrong. It still needs proxyUrl when using bulk API, surely it accepts bulk API request but it redirects to other domain than Visualforce page. I think @jimrae 's last setting is the one how to connect to bulk API from Visualforce page.

conn = new jsforce.Connection({ 
    accessToken: '{!$Api.Session_Id}',
    proxyUrl: '/services/proxy'
});

[jimrae]

Thank you for the validation. That is the way I ended up setting up the configuration for my project.