Hi everyone,
I'd like to create a my own custom model. 
I did it using cURL without issues. Now I'm trying to get the same results using Javascript to have a token, create e datamodel, train a dataset ad have a prediction programmatically.
I'm having issues gettin a token from an ajax request.
This is my code to generate an assertion a get a token: 

function generate_assertion(sub, exp, privKey) {
            var header = JSON.stringify({
              "alg": "RS256",
              "typ": "JWT"
            });

            var timeInMillis = Math.round(+new Date() / 1000);
            exp = timeInMillis + (parseInt(exp) * 60);
            var domain = "https://api.dev.einstein.ai"
            

            var payload = {
              "sub": sub,
              "aud": domain + "/v1/oauth2/token",
              "exp": exp
            };
            assertion = KJUR.jws.JWS.sign(null, header, payload, privKey);
            var tokenPayload = {
              "assertion": assertion,
              "grant_type": "urn:ietf:params:oauth:grant-type:jwt-bearer"
            };
            
            return tokenPayload;
      }
      
      
        // On form submit generate the access token
        function getToken() {
        
            var sub = 'iodicepasquale85@gmail.com';
            var exp = 7200;
            var tokenPayload = "";

            try {
            tokenPayload = generate_assertion(sub, exp, privKey);
            } catch (err) {
                console.log("ERROR: ", err);
            return;
            }

            $.ajax({
            type: 'post',
            url: 'https://api.einstein.ai/v1/oauth2/token',
            headers: 'Content-type : application/x-www-form-urlencoded',
            data: tokenPayload,
            success: function (data) {
                console.log("TOKEN: " , data["access_token"]);
            },
            error: function (data) {
                  console.log("ERROR: " , data);
            }    
            });
        }

Where "privKey" is the private key contained in the "predictive_services.pem" file I downloaded when I signed up for an account.

 "generate_assertion" Methos seems work fine. I'm having this ERROR in ajax request:

"Response to preflight request doesn't pass access control check: No 'Access-Control-Allow-Origin' header is present on the requested resource."

Best regards,
Pasquale