Getting the Height of iFrame Content

Question

I am using a commenting script similar to Disqus. I embed the iFrame in some pages, including a Modal. I set scrolling to no and want to display the content of iFrame source in full without scrolling. I can do this by setting the iFrame height to some large number. However, I need this to be dynamic, I need to figure out the height of the content of the iFrame, or have the container shrinks in height depending on source content. How do I do that. I tried number of JQuery functions around and none seems to work.

Preparing iframe code

  html = "<div class='ui items'><div class='item'><div class='ui tiny

        image'><img class = 'th mini-img' style = 'height:50px; width:50px;' 

        src='"+img+"'></div><div class='middle aligned content'><a 

        class='header'>"+name+"</a><div class='meta'><span class='cinema'><?php 

        echo $this->__('Inspiration by Visitor');?></span></div></div></div>

        </div>";

Putting iframe in a modal made by semantic-ui framework, on a click to some button

 <div class="ui long modal" id="easycomment_modal">

  <div class="header">
Profile Picture
 </div>

</div>

      <div class="description">
  <div class="ui header">We've auto-chosen a profile image for you.</div>
   <div class="cmt_contain"></div>
</div>
    </div>

    <div class="actions">
<div class="ui positive right labeled icon button">
  Yep, that's me
  <i class="checkmark icon"></i>
</div>

    </div>
  </div>