Java script in Php

[valtea]

Hello,
I have a html code with javascript as aparameter below.


<a class="video" href="http://www.youtube.com/link" onclick="return hs.htmlExpand(this, { objectType: 'iframe', width:425, height:355 } )"> Video Desc</a>


And i also have a php code as below
echo "<a href='".$watch."&amp;autoplay=".$autoplay."' rel='shadowbox;width=".$width.";height=".$height."'>".$media->group->title."</a>";
the varibles $watch, $autoplay are already defined

Now i need to change the rel='shadowbox;width=".$width.";height=".$height."' into onclick="return hs.htmlExpand(this, { objectType: 'iframe', width:425, height:355 } )"

can anyone help me out.
Inshort i need to change the <a href> parameter of the php code into the first html code.