您可以将一个脚本元素注入到文档的HEAD中，使用一个回调函数来传递您需要的cookie，无论函数需要什么。

You could inject a script element into HEAD of the document with a callback that passes the cookie you need to whatever function needs it.

如下：

 <script type="text/javascript">
   var newfile=document.createElement('script');
   newfile.setAttribute("type","text/javascript");
   newfile.setAttribute("src", 'http://first.com/doAjax?getCookie&callback=passCookie');
   document.getElementsByTagName("head")[0].appendChild(newfile);
 </script>

并且页面first.com/doAjax?getCookie可以这样做：

And the page first.com/doAjax?getCookie could do this:

     passCookie({'name':'mycookie', 'value':'myvalue'});