When I try to link the newly created article with a Wikidata item, it's proposed to specify a project and an article in it.
I use HTTPS protocol in Wikipedia, and WikidataClient tries to access foreign Wikipedia APIs via HTTP. Thus it's been blocked by Chrome:
It appears that wbSiteDetails is not populated the right way: apiUrl and pageUrl should keep the current protocol, shouldn't they? We could use protocol independent URLs, but I'm not sure whether jQuery interprets them correctly in ajax requests.