CORS and javascript

Hi.

As you may have guessed it, I'm having CORS issues while trying to make API calls cross site.

CORS IS enabled in IIS, but I keep getting the CORS errors. The only way I've been able to get it to not show is changing from json to jsonp. But then I get a CORB message, and it also returns nothing anyway.

Can anyone provide a known working example using $ajax or fetch, or anything that works in javascript?

Thank you in advance!