<script type="text/javascript">
document.getElementById("frame1").frameBorder="0";
document.getElementById("frame1").frameBorder="1";
<iframe src="/example/hdom/frame_a.html" id="frame1"></iframe>
<input type="button" onclick="removeBorder()" value="Remove border" />
<input type="button" onclick="restoreBorder()" value="Restore border" />