Please give more details on what are you accessing? How are you accessing? Where is your server hosted? Does it have the setting Access-Control-Allow-Origin: *? Any Proxy?
as J mentioned, your server needs to allow.. You can set it up to be open as much as,
Access-Control-Allow-Origin: *
or restrict it to,
Access-Control-Allow-Origin: http://localhost:3000
You can also make it working by sending the request to a Proxy instead.