Call Rest services of Mendix from another application.
You should be able to either implement your own rest handler or modify the one in your project to support CORS
I assume your web page comes from a different server than the Mendix server. The browser will not allow service calls to another domain. You may need to call a service on the server that serves the web page and from that server call the Mendix service.
If you google the error, you will find quite a few pointers to help you out.