random background image not loading

I am trying to activate the random background image for the "something" element, but without success, can anyone give a suggestion what I am doing wrong ? This is from the content-single-product.phpWoocommerce plugin

<div class="item-layout" id="something">
<script type="text/javascript">
var images = [
    "http://ift.tt/1Du9udu",
    "http://ift.tt/19O7Fdj",
    "http://ift.tt/1Du9udw",
    "http://ift.tt/1Du9utK"
];

$("#something").css("background", "url(" + images[Math.floor(Math.random() * images.length)] + ")");
</script>
    <div itemscope itemtype="http://ift.tt/GXPmjp" id="product-<?php the_ID(); ?>" <?php post_class(); ?>>

        <?php ...
        ?>

        <div class="summary">

            <?php ...               ?>

        </div>
    </div>
</div>
<div style="clear:both;"></div>
        <?php 
            ...
        ?>

        <?php do_action('woocommerce_after_single_product'); // upsell ?>

    </div><!-- #product-<?php the_ID(); ?> -->

The css for #something is width:100%; height:400px;