title: Change ajax page url on multisite
body: <p>I have an ajax page on a multisite. The problem is at the moment when I have this code my second site pulls in the main sites urls with ajax</p>
  
  <pre><code> jQuery.ajax({
      type: 'post',
      url: '/ajax',
      data: {
          postId: postid,
      },            
  </code></pre>
  
  <p>I tried something like this code below and that helps me get the right site url but it also includes the current page. So for example something like this POST <a href="http://bla.bom.net/current-page/ajax" rel="nofollow">http://bla.bom.net/current-page/ajax</a></p>
  
  <p>I need it to bring in the ajax page without any current page in the url
  so for example  POST <a href="http://bla.bom.net/ajax" rel="nofollow">http://bla.bom.net/ajax</a></p>
  
  <pre><code> jQuery.ajax({
      type: 'post',
      url: document.URL+'/ajax',
      data: {
           postId: postid,
      }
  </code></pre>