Five common HTTP status codes and their meanings
200: The request was successful and the desired response header or data body is returned with this response.
303: Tells the client to use a different URL to get the data.
400: request format error 1. Semantic error, the current request cannot be understood by the server, otherwise the client should not repeat the request, 2. The request parameters are incorrect.
404: Request failed because requested data is not found on the server.
500: The background server is out of order.
More status codes
100: Initializing (normally invisible)
101: Switching protocols (provided by webSocket browser)
202: Indicates acceptance
301: Permanent redirect/permanent transfer
302: Temporary redirect/temporary transfer
304: The content obtained is to read the data in the cache, and will be checked by the server every time
401: Unauthenticated, no login
403: No access permission
503: The server is overloaded