title: Does CORS error related to front end or back end?
body: <p>Does CORS error is related to front end or back end? If it's from front end, how to handle it? I'm getting <a href="https://i.stack.imgur.com/hzdke.png." rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/hzdke.png." alt="Error"></a></p>
  
  <p>I got little bit move forward. Now, i'm getting <code>No 'Access-Control-Allow-Origin' header is present on the requested resource. Origin 'null' is therefore not allowed access</code> error. How to add header to it?</p>
  
  <p><strong>My Ajax call is:</strong></p>
  
  <pre><code>$.ajax({
                      type: "POST",
                      url: url,
                      //contentType: "application/json; charset=utf-8",
                      crossDomain:true,
  
                      data: JSON.stringify(feederData),
                      dataType: "json",
                      success: function (data) {
                          console.log(data);
                          if (data === true) {
                              alert();
                          }
                      },
                      error: function (a, b, c) {
                          console.log(a);
                          alert(a);
                      }
                  });
  </code></pre>