How can I solve cross domain problems？

I've set the header and type of Ajax, but when I make a request, I still report an error. I don't understand why. Is someone in the same situation as me?

This is a problem that has been bothering me. Can I use C3P offline and run it through my local domain name? If so, where to see it. Thank you very much.

In my case, I am usually enabling something on the server-side. I've used the below guide in the past. Do you control the server?

enable-cors.org/server.html

See the AJAX manual entry which covers this.