go servemux

misc

status codes

In general you can lookup an existing http status code constant in http/status.go. This might be prefered over writing the number directly.

You can only call w.WriteHeader once per responce. Any additional calls and go will log a warning message. Additionally, if you do not call it before the first call to w.Write a 200 OK code will be sent.

auto generated headers

When sending a responce Go will automatically set three system-generated headers: Date and Content-Length and Content-Type.

The Content-Type header is particuarly interesting. Go will attempt to set the correct one for you by content sniffing the responce body with the http.DetectContentType() function. If it can't guess the content type, go will fall back to setting Content-Type: application/octec-stream instead. Notable, this happens by default with json. You can of course manually correct this:

w.Header().Set("Content-Type", "application/json")
w.Write([]byte(`{"name":"Alex"}`))