Appending <script> elements to div and execute dynamically with PHP & Javascript [duplicate]

My sample php $advert variable as follows;

<script src="http://ad.example.com/scripts/rp.js" type="text/javascript"></script><script src="http://ad.example.com/scripts/rp.js" type="text/javascript"></script>
<script type="text/javascript">
    document.write("<"+"script src='http://ad.example.com/rpgetad.ashx?tt=t_&ciid=9775202&rnd="+Math.random()%99999999+"'></"+"script>");
</script>

I want to create js variable with it.

var advert = "<?php echo rawurlencode($advert); ?>";

then i want to decode and append it to specified div and execute it.

var content = decodeURIComponent(advert);
document.getElementById("mydiv").innerHTML = content;

But when i try it doesn't work.

I also tried php's json_encode() and $('<div/>').html(contents).text() decode methods.

I need to do this with javascript if it is posible.

I am caching html responses. Advertising codes from partners are changing every day. So i dont want to destroy page's cache every time. I am generating seperated js file with php to do that.