You need to trigger JSONP behavior with $.getJSON()
by adding &callback=?
on the querystring, like this:
$.getJSON("http://en.wikipedia.org/w/api.php?action=query&prop=revisions&rvprop=content&titles="+title+"&format=json&callback=?", function(data) {
doSomethingWith(data);
});
Without using JSONP you’re hitting the same-origin policy which is blocking the XmlHttpRequest from getting any data back.