I have this code at the top of my index.php file to add a timestamp to my CSS file so that latest version is always rendered.

$version = filemtime(JPATH_THEMES . '/' . $this->template . '/css/template.css');
JHtml::_('stylesheet', 'template.css', array('version' => $version, 'relative' => true));

However, I would also like to preload the file and can't work out how to add rel="preload" and as="style" and onload="this.rel='stylesheet'" to the above.

  • I have heard this technique called a "cache buster". Apr 13, 2023 at 21:49
  • Quite possibly. But when I've made changes to a CSS file I need them to be displayed on the front-end straight away, not in a month's time.
    – Gillian
    Apr 14, 2023 at 15:37

1 Answer 1


In Joomla 4 you can use the WebAsset Manager instead of HTMLHelper(JHtml).

In your template's index.php file:

$wa  = $this->getWebAssetManager();

$version = filemtime(JPATH_ROOT . '/media/templates/site/mytemplate/css/mymain.css');

$wa->registerAndUseStyle('template.mytemplate.mymmain', "mymain.css", ['version' => $version, 'relative' => true], ['rel' => "preload", 'as' => "style", 'onload' => "this.rel='stylesheet'" ], []);

in this example code, my css file is called: mymain.css and it is in media folder under templates/site/mytemplate/css subfolder as it should be. This has worked for me.

It is same with HTMLHelper:

use Joomla\CMS\HTML\HTMLHelper;

$version = filemtime(JPATH_ROOT . '/media/templates/site/mytemplate/css/mymain.css');

HTMLHelper::stylesheet('mymain.css', $options = ['version' => $version, 'relative' => true, ], $attribs = ['rel' => "preload", 'as' => "style", 'onload' => "this.rel='stylesheet'"]);


<link href="/media/templates/site/mytemplate/css/mymain.css?1681564883" rel="preload" as="style" onload="this.rel='stylesheet'" />
  • Thanks. I tried this several times unsuccessfully, but then I removed ->useStyle('template.mytemplate') from $wa->useStyle('template.mytemplate') ->useStyle('template.user') ->useScript('template.user'); it worked. I think in Cassiopeia the equivalent is >usePreset('template.cassiopeia.' . ($this->direction === 'rtl' ? 'rtl' : 'ltr'))
    – Gillian
    Apr 18, 2023 at 10:47
  • @Gillian - Sure, for me both of my examples work without any problem. But the question was about how to add timestamp and attributes to stylesheet links…
    – Zollie
    Apr 18, 2023 at 11:13
  • 1
    Of course. I added my comment in case anyone else tried and had the same difficulty I did and could see why. I'll accept your answer.
    – Gillian
    Apr 18, 2023 at 11:19

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