1. @DomName('XMLHttpRequest.open')
  2. @DocsEditable()
void open(String method, String url, { bool async, String user, String password })

Specify the desired url, and method to use in making the request.

By default the request is done asyncronously, with no user or password authentication information. If async is false, the request will be send synchronously.

Calling open again on a currently active request is equivalent to calling abort.

Note: Most simple HTTP requests can be accomplished using the getString, request, requestCrossOrigin, or postFormData methods. Use of this open method is intended only for more complex HTTP requests where finer-grained control is needed.

Source 

@DomName('XMLHttpRequest.open')
@DocsEditable()
void open(String method, String url,
    {bool async, String user, String password}) {
  if (async == null && user == null && password == null) {
    _blink.BlinkXMLHttpRequest.instance.open_Callback_2_(this, method, url);
  } else {
    _blink.BlinkXMLHttpRequest.instance
        .open_Callback_5_(this, method, url, async, user, password);
  }
}