An Ajax http request has 5 states as your reference documents:
0 UNSENT open() has not been called yet.
1 OPENED send() has been called.
2 HEADERS_RECEIVED send() has been called, and headers and status are available.
3 LOADING Downloading; responseText holds partial data.
4 DONE The operation is complete.
State 4 means that the request had been sent, the server had finished returning the response and the browser had finished downloading the response content.
So, it is right to say that the AJAX call has completed.