I am using both the twitter tweet button, and the facebook like button
<a href="http://twitter.com/share"
class="twitter-share-button"
data-url="http://example.com"
data-text="some text"
data-count="horizontal"
data-via="someone">Tweet
</a>
<script type="text/javascript" src="http://platform.twitter.com/widgets.js"></script>
<script src="http://connect.facebook.net/en_US/all.js#xfbml=1"></script>
<fb:like
class="fbShare"
href="http://example.com"
font="" send="true"
layout="button_count"
show_faces="false">
</fb:like>
But both of them are spitting out Cross domain Errors, Not one or two, but continuously.
the actual errors (with substitutions) are
Unsafe JavaScript attempt to access
frame with URL
https://www.facebook.com/plugins/like.php?channel_url=http%3A%2F%2Fstatic.ak.fbcdn.net%2Fconnect%2Fxd_proxy.php%3Fversion%3D3%23cb%3Df3cde04b84%26origin%3Dhttp%253A%252F%252Fexample.com%252Ff20b9fb1fc%26relation%3Dparent.parent%26transport%3Dpostmessage&href=http%253A%252F%252Fexample.com%252F&layout=button_count&locale=en_US&node_type=link&sdk=joey&send=true&show_faces=false&width=150
from frame with URL
http://example.com/. Domains,
protocols and ports must match.Unsafe JavaScript attempt to access
frame with URL
http://platform0.twitter.com/widgets/tweet_button.html?_=1308700896075&count=horizontal&id=twitter_tweet_button_0&lang=en&original_referer=http%3A%2F%2Fexample.com%2F&text=some text&url=http%3A%2F%2Fexample.com%2F&via=someone
from frame with URL
http://example.com/. Domains,
protocols and ports must match.
Best Answer
This seems to be a bug with the Twitter button code that you would probably want to log with Twitter. It seems to be attempting to traverse every dom object on the page and it is not able to access the Facebook iframe object. For example, if you also add the Google +1 button, it will now throw an additional similar message but for Google related urls.
The functionality doesn't seem to be impacted though so I would just ignore it. Any site using this Tweet button and also another iframe from a different server (eg Facebook/G+ button) will also have the same issue (for example try any page on mashable.com). If you do not want to just ignore it, you could remove the Twitter javascript reference and create a custom Tweet button as mentioned on their Tweet button page, by using javascript to popup this url format: http://twitter.com/share?url=http%3A%2F%2Fdev.twitter.com%2Fpages%2Ftweet-button, with the downside of this being that the tweet count won't show on your page.