I have noticed that every answer to Success (200) is also a response No Content (204) .
I was curious and went to search the MDN on status 200 , the The only thing that says successful results for a PUT and a DELETE should return a 204 . I have made a request GET and after that I have a request with the verb OPTIONS returning a status 204 .
Because a return with status code 200 also returns a 204 with the verb OPTIONS ?
Return 204 is pure convention, it means a successful response without any content (body).
The OPTIONS request itself is a "special" request made by the browser when you request resources from another domain ( cross-domain ). It serves to check if you are able to make this request to another domain.
It sends the headers Access-Control-Request-Method , Access-Control-Request-Headers and Origin .
Access-Control-* ) that define what is available for the given endpoint .
The name of this is preflight request .
You can see more details on MDN .
In your example, a request with the header Access-Control-Request-Headers is set to Authorization and Access-Control-Request-Method set to GET .
The server responded by saying that it is all right (204) and that you can send the header Authorization that it will be accepted and interpreted, in addition, there is the header Access-Control-Allow-Origin which defines this endpoint can be called from any source.