post request never returning fetch api js

Question

Hello guys I'm trying to make a post request using js fetch api but the problem it's not returning. It never enters the callback in the then function. Can somebody tell me what is it that is going wrong

fetch('http://ready.buzlin.com/buzlinApp/checkout/checkout.php', {
              method: 'POST',
              headers: {
                  'Content-Type': 'application/json',

              },
              body: s
          }).then((response) => {
              console.log("ok");
          });

If I make the same call using postman it works

Answer 1

This is a CORS problem, a security measure adopted by browsers (which explains why you could do it via Postman).

Basically, your browser sends a preflight request to the server to know what it is expecting, and the server isn't returning your origin as an acceptable one (Access-Control-Allow-Origin Header).

This API probably does not support CORS. That means your request will only work if made from server-side, secure browsers will not allow it.