title: dynamically change facebook og image in a fancybox share button
body: <p><strong>The goal :<br/></strong>
  I would like to have a share button in my fancybox that share the image I'm looking at with the correct image name in the Facebook sharer. I would like that when a user click on this in Facebook, he arrives on an opened Fancybox with the correct image.</p>
  
  <p><strong>The problem :<br/></strong>
  I have a gallery with Jquery FancyBox (<a href="http://fancyapps.com/fancybox/" rel="nofollow">http://fancyapps.com/fancybox/</a>). I added a share button with the code I find in this fiddle (<a href="http://jsfiddle.net/G5TC3/" rel="nofollow">http://jsfiddle.net/G5TC3/</a>).
  My share button works, but get the meta og from the site and I want to have the og:image from the image I'm looking at.</p>
  
  <pre><code>$(".fancybox")
  .attr('rel', 'gallery')
  .fancybox({
      beforeShow: function () {
          if (this.title) {
  
              // Add FaceBook like button
              this.title += '&lt;iframe src="//www.facebook.com/plugins/like.php?href=' + this.href + '&amp;amp;layout=button_count&amp;amp;show_faces=true&amp;amp;width=500&amp;amp;action=like&amp;amp;font&amp;amp;colorscheme=light&amp;amp;height=23" scrolling="no" frameborder="0" style="border:none; overflow:hidden; width:110px; height:23px;" allowTransparency="true"&gt;&lt;/iframe&gt;';
          }
      },
      helpers : {
          title : {
              type: 'inside'
          }
      }  
  });
  </code></pre>
  
  <p>For the user who clicks on my link and arrives on an opened Facybox with the correct image I have no idea how to do that and if it's possible.</p>
  
  <p><strong>What I know: <br/></strong>
  I know that I have to have uniques URL for each images and I think I have it. ex from my site:<br/>
  www.myURL.com/images/gallery/myimages_1.jpg<br/>
  www.myURL.com/images/gallery/myimages_2.jpg<br/></p>
  
  <p>Is it correct?</p>
  
  <p>I think I have to change the "this.href" in the sharer by the image url. First is it correct? And second (sorry I'm new in javascript) how can I do that?</p>
  
  <p>I hope somebody could help me. Sorry for my English I'm trying to write my best English :)
  If you need more information please do not hesitate.</p>
  
  <p>Thanks</p>
  
  <p>[EDIT]:</p>
  
  <p>I add this script on the gallery page</p>
  
  <pre><code>$(function()
  {
      $('.thumbs').click(function()
      {
          $tempImgName = $(this).attr('id');
          $tempUrl = this.href + '/images/thumbs/' + $tempImgName;
          $meta = document.getElementById('facebook');
          $meta.setAttribute("content",$tempUrl);
      });
  });
  </code></pre>
  
  <p>So when I click on a thumbsnail (with the class .thumbs) I get the image URL and I change the meta (with the facebook Id). It works but I think Facebook check the meta when the page load so how can I force Facebook to recheck my meta to take the good thumbs to share?</p>