make iframe height dynamic based on content inside- JQUERY/Javascript

You can retrieve the height of the IFRAME‘s content by using:
contentWindow.document.body.scrollHeight

After the IFRAME is loaded, you can then change the height by doing the following:

<script type="text/javascript">
  function iframeLoaded() {
      var iFrameID = document.getElementById('idIframe');
      if(iFrameID) {
            // here you can make the height, I delete it first, then I make it again
            iFrameID.height = "";
            iFrameID.height = iFrameID.contentWindow.document.body.scrollHeight + "px";
      }   
  }
</script>   

Then, on the IFRAME tag, you hook up the handler like this:

<iframe id="idIframe" onload="iframeLoaded()" ...

I had a situation a while ago where I additionally needed to call iframeLoaded from the IFRAME itself after a form-submission occurred within. You can accomplish that by doing the following within the IFRAME‘s content scripts:

parent.iframeLoaded();