Image preloading helper for symfony.

PreloadHelper.php

<?php
/**
 * Returns a html to preload images using jQuery.
 *
 * @param array $urls An array of image URLs
 * @return string HTML contents
 */
function preload_images($urls)
{
    if (!is_array($urls)) {
        $urls = array($urls);
    }

    $lines = array();
    $lines[] = '<script type="text/javascript">';
    $lines[] = '//<![CDATA[';
    foreach ($urls as $url) {
        $lines[] = "jQuery('<img>').attr('src', '{$url}');";
    }
    $lines[] = '//]]>';
    $lines[] = '</script>';

    return implode("\n", $lines);
}