RxJs: Adapt jQuery.getJSON to an Rx.Observable

jquery.getjson.observable.js

function getJSON(url, data) {
  return Rx.Observable.create(observer => {
    var canceled = false;
    if (!canceled) {
      jQuery.getJSON(url, data).
        done(data => {
          observer.onNext(data);
          observer.onCompleted();
        }).
        fail(err => observer.onError(err));
    }
    return () => canceled = true;
  });
}

getJSON('https://api.ipify.org', { format: 'json' }).forEach(e => console.log(e));