Javascript - No 'Access-Control-Allow-Origin' header is present on the requested resource

Question

I need to send data through XmlHttpRequest from JavaScript to Python server. Because I\'m using localhost, I need to use CORS. I\'m using the Flask framework an

Answer 1

The Access-Control-Allow-Origin must be sent by the server, not by you. When you make a call to another domain, the browser checks whether this header is returned by the server. If it isn't, the call fails. I don't know Python, so I don't know how to make your server send this header, or even if you can modify the server at all.