post hidden field different PHP page

I want post selected row hidden field other PHP page.
I get this field like this :

obj.getProperty('data/text' , obj.getProperty('selection/index'), 0);
  and it gives me the right variable. But now I cannot post this

Example:

<form action="<?=$PHP_SELF;?>" method="post">
<input type="hidden" name="p" value="myvar"/>
<script language="JavaScript" type="text/javascript">
<!--
document.write('<input type=hidden name=id value=' +obj.getProperty('data/text' , obj.getProperty('selection/index'), 0)+'>');
//-->
</script>
<input type="submit" value="Edit"/>
</form>
  and like this it doesnt work at all. I'm not so good in Javascript and maybe I make some mistakes. Solutions?