Possible Duplicate:

How to get elements with multiple classes

Working on a bit of javascript code that sets the current URL of the referring page to pass into an iframe widget. No control over the code of the page on which the javascript resides, except for the one bit of javascript code.

An example of the element value I need to grab is as follows:

<div id=new_p_2FRolls-Royce_p_2F2013-Rolls-Royce-Phantom_p_2BDrophead_p_2BCoupe-4a5be12c0a0a00650143b598a45df25d_p_2Ehtm class=page NEW_VEHICLE_DETAILS current>

What I'm trying to do is select the div by combining classes page and current. In this example, NEW_VEHICLE_DETAILS is unique to this page, and varies on other pages. I would like to create a consistent bit of code that doesn't have to be altered for each page as it is currently. Here is the code I am using right now:

<div id=build_iframe></div>

<script>

var pageid = document.getElementsByClassName('NEW_VEHICLE_DETAILS')[0].id;

var currenturl = 'http://m.whateverwebsite.com/index.htm#'+pageid;

var shareurl = escape(currenturl);

document.getElementById('build_iframe').innerHTML = '<iframe style=border:1px;width:100%;height:110px; src=http://widget.mywidgetwebsite.com/share-tool/?current_url='+shareurl+'></iframe>';

</script>

jQuery is not an option in this case. How can I get the value of the ID by selecting only the element with BOTH page and current classes set?