Unable to get response from an ajax api call getting cors error ,working fine in post man. I have added the cors headers in request

Question

I am using this code:-

  var saveData=$.ajax({
                            url: "api",
                            headers: {
                                "Access-Control-Allow-Origin":"*",
                                "Access-Control-Request-Headers": "x-requested-with",
                                 "Access-Control-Allow-Methods": "GET, POST, PATCH, PUT,DELETE,OPTIONS",
                                 "Access-Control-Allow-Headers": "Origin, Content-Type, X-Auth-Token",
                                 "Accept":"application/json"
                                    },
                    type: 'POST',
                         dataType: 'application/octet-stream',
    contentType: 'image/jpeg',
    processData: false,
    data: binaryData,
    success: function (data) {
      alert(data);
    },
    error: function(){
      alert("Cannot get data");
    }
});

But I am getting this:- Access to XMLHttpRequest at 'api/bintest1.jpeg' from origin 'null' has been blocked by CORS policy: Response to preflight request doesn't pass access control check: No 'Access-Control-Allow-Origin' header is present on the requested resource.

But it is working fine in postman:-