Migrating frames based code to non frame based code

I am migrating some old frames html code and its corresponding javascript to non-frame based code.

The old frames based html had something like:

<frameset rows="100%,0,0,0,0" border="0">
    <frame src="roster.html" name="jwc_main" marginwidth="0" marginheight="0" scrolling="no">
  </frameset> 

Iframe code in html:

<iframe src="iRoster.html" name="iRoster" id="iRoster" scrolling="auto"    
style="width:100%;height:100%;border:2px groove;" frameborder=0>

and there was a javascript method where iframe within the frame html was accessed like:

var fmd = frames["jwc_main"].iRoster.document;

and this fmd variable was then used like:

fmd.getElementById('display').innerHTML = '';

What should do i need to do in order to change this code?

I found the solution, used

var fmd = iRoster.document;

Thanks