Adding JavaScript and CSS to the page

From Joomla! Documentation

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This is one of a series of API Guides, which aim to help you understand how to use the Joomla APIs through providing detailed explanations and sample code which you can easily install and run.

Inserting from a File[edit]

Joomla allows you to add JavaScript and CSS files to your HTML document, and it puts the associated <script> and <link> elements within the HTML <head> section. To do this you call the addScript and addStyleSheet methods of the Joomla object which represents the HTML document. Since Joomla! buffers all the HTML-related data that makes up a page before output, it is possible to call these methods anywhere within your code.

First, get a reference to the current document object:

use Joomla\CMS\Factory;
$document = Factory::getDocument();
// above 2 lines are equivalent to the older form: $document = JFactory::getDocument();

Then for a style sheet, use this code:


To add a JavaScript file, use this code:


where $url is the variable containing the full path to the JavaScript or CSS file. For example: JUri::base() . 'templates/custom/js/sample.js'

Note this will not include Mootools or jQuery. If your script requires Mootools or jQuery see JavaScript Frameworks for full details on how to include them. (Note that jQuery can only be included natively on Joomla! 3.0+.) It used to be possible to do this with JHTML, however, this was deprecated in Joomla 2.5 and removed in Joomla 3.x.

$options and $attributes Parameters[edit]

You can add $options and $attributes parameters to the above methods. The $options control overall how the <script> and <link> elements are output while the $attributes get set as HTML attributes within those tags. (Note that although there are Deprecated markers against the addScript and addStyleSheet methods of the Joomla Document API, these markers refer just to the signature of these methods; the form of the signature using $options and $attributes parameters is not deprecated). The $options parameter should be an array and 2 different options are currently supported:

  • version => auto If this is set then a 'media version' is appended as a query parameter to the CSS or JavaScript URL within the <script> or <link> element. This is a string (an md5 hash) that is generated from factors including the Joomla version, your Joomla instance secret and the date/time at which the media version was generated. The media version is regenerated whenever anything is installed on the Joomla instance. Its purpose is to force browsers to reload the CSS and JavaScript files instead of using possibly outdated versions from cache.

For example

$document->addStyleSheet("...demo.css", array('version'=>'auto'));
// leads to something like
// <link href="...demo.css?37e343bbb4073e0dfe5b1eb40b6" rel="stylesheet">

The string of characters after the ? is the md5 hash, which will change when extensions or Joomla itself are installed/upgraded/uninstalled.

  • conditional' => 'lt IE 9 (as an example). This outputs the <script> or <link> within a Conditional Comment which earlier versions of Internet Explorer interpreted.

For example

$document->addScript("...demo.js", array('conditional'=>'lt IE 9'));
// leads to
// <!--[if lt IE 9]><script src="...demo.js"></script><![endif]-->

The $attributes parameter should also be an array, and these are mapped to be HTML attributes of the <script> or <link> element. For example,

$document->addScript("...demo.js", array(), array('async'=>'async'));
// leads to
// <script src="...demo.js" async></script>

Adding the Options to Your JavaScript Code[edit]

≥ 3.7
Only available in Joomla! 3.7 and higher

(Note that these Options are different from the $options parameter described above).

Beside adding inline scripts, Joomla! provides a mechanism to store the options in the "optionsStorage". This allows you to nicely manage existing options on the server side and on the client side. It also allows you to place all JavaScript logic into the JavaScript file, which will be cached by browser.

Joomla! uses a special mechanism for "lazy loading" the options on the client side. It doesn't use inline JavaScript, which is good for page rendering speed, and makes your site more friendly to the Speed Testers (e.g. Google).

The use of "optionsStorage" is preferred over inline JavaScript for adding the script options.

Example of Use

Add the script options to your module:

$document = JFactory::getDocument();
$document->addScriptOptions('mod_example', array(
    'colors' => array('selector' => 'body', 'color' => 'orange'),
    'sliderOptions' => array('selector' => '.my-slider', 'timeout' => 300, 'fx' => 'fade')

Access your options on the client side:

var myOptions = Joomla.getOptions('mod_example');
console.log(myOptions.colors); // Print your options in the browser console.

Override the options on server side. (Possible until the head rendering.):

$document  = JFactory::getDocument();
// Get existing options
$myOptions = $document->getScriptOptions('mod_example');
// Change the value
$myOptions['colors'] = array('selector' => 'body', 'color' => 'green');
// Set new options
$document->addScriptOptions('mod_example', $myOptions);

Passing Language Strings to JavaScript[edit]

There are cases when you may want to output an error message in your JavaScript code and want to use the Joomla mechanism of language strings. You could manage this by using addScriptOptions to pass down each language string you need, but Joomla provides a more succinct solution. To pass a language string to JavaScript do in your PHP code, for example,

JText::script('JLIB_APPLICATION_ERROR_ACCESS_FORBIDDEN'); Then in your JavaScript code you can do:

var message = Joomla.JText._('JLIB_APPLICATION_ERROR_ACCESS_FORBIDDEN'); to obtain in the user's language the text message associated with the language constant. Obviously certain language strings have embedded %s characters, so in your JavaScript code you will have to handle that, eg using an external JavaScript sprintf library or string replace, etc.

Inserting Inline Scripts from Within a PHP File[edit]

If your JavaScript or CSS are generated using PHP, you can add the script or style sheet directly into the head of your document:

$document = JFactory::getDocument();

// Add Javascript
    window.event("domready", function() {
        alert("An inline JavaScript Declaration");

// Add styles
$style = 'body {'
        . 'background: #00ff00;'
        . 'color: rgb(0,0,255);'
        . '}';

JavaScript Example[edit]

For example, the following code is used to define a custom tool tip that takes advantage of Mootools.

function getToolTipJS($toolTipVarName, $toolTipClassName){
    $javascript = 'window.addEvent(\"domready\", function(){' ."\n";
    $javascript .= "\t"  .'var $toolTipVarName = new Tips($$("' . $toolTipVarName .'"), {' ."\n";
    $javascript .= "\t\t"   .'className: "' .$toolTipClassName .'",' ."\n";
    $javascript .= "\t\t"   .'initialize: function(){' ."\n";
    $javascript .= "\t\t\t"    .'this.fx = new Fx.Style(this.toolTip, "opacity", {duration: 500, wait: false}).set(0);' ."\n";
    $javascript .= "\t\t"   .'},' ."\n";
    $javascript .= "\t\t"   .'onShow: function(toolTip){' ."\n";
    $javascript .= "\t\t\t"    .'this.fx.start(1);' ."\n";
    $javascript .= "\t\t"   .'},' ."\n";
    $javascript .= "\t\t"   .'onHide: function(toolTip) {' ."\n";
    $javascript .= "\t\t\t"    .'this.fx.start(0);' ."\n";
    $javascript .= "\t\t"   .'}' ."\n";
    $javascript .= "\t"  .'});' ."\n";
    $javascript .= '});' ."\n\n";
    return $javascript;

$document = JFactory::getDocument();

Note that in order for this JavaScript to be useful, it is necessary to include the appropriate class name in the HTML, as well as providing the mytooltip.css file. Both are outside the scope of this article.

CSS Examples[edit]

This is also useful if you are inserting a form field of CSS into your code. For example, in a module you might want a user to choose the colour of the border. Call the form field's value and assign it a variable $bordercolor in mod_example.php. Then in tmpl/default.php you can include the following:

$document = JFactory::getDocument();
$style = '#example {
	border-color:#' . $bordercolor . ';
$document->addStyleDeclaration( $style );

Here mod_example.css contains the CSS file of any non-parameter based styles. Then the bordercolor parameter/form field is added in separately.

Add Custom Tag[edit]

There will be some occasions where even these functions are not flexible enough, as they are limited to writing the contents of <script /> or <style /> tags, and cannot add anything outside those tags. One example would be the inclusion of a style sheet link within conditional comments, so that it is picked up only by Internet Explorer 6 and earlier. To do this, use $document->addCustomTag:

$stylelink = '<!--[if lte IE 6]>' ."\n";
$stylelink .= '<link rel="stylesheet" href="../css/IEonly.css" />' ."\n";
$stylelink .= '<![endif]-->' ."\n";

$document = JFactory::getDocument();

If it was necessary to include other conditional CSS, always include the addCustomTag method after it is declared.

Sample Module Code[edit]

Below is the code for a simple Joomla module which you can install and run to demonstrate adding CSS and JavaScript, and can adapt to experiment with the concepts above. If you are unsure about development and installing a Joomla module then following the tutorial at Creating a simple module will help. In a folder mod_css_js_demo create the following 4 files:


<?xml version="1.0" encoding="utf-8"?>
<extension type="module" version="3.1" client="site" method="upgrade">
    <name>css js demo</name>
    <description>Code for including JS and CSS links</description>
        <filename module="mod_css_js_demo">mod_css_js_demo.php</filename>


defined('_JEXEC') or die('Restricted Access');

use Joomla\CMS\Factory;

$document = Factory::getDocument();

$options = array("version" => "auto");
$attributes = array("defer" => "defer");
$document->addScript(JURI::root() . "modules/mod_css_js_demo/demo.js", $options, $attributes);
$document->addStyleSheet(JURI::root() . "modules/mod_css_js_demo/demo.css", $options);

$document->addScriptOptions('my_vars', array('id' => "css-js-demo-id2"));


echo '<h1 id="css-js-demo-id1">Hello World!</h3>';
echo '<button id="css-js-demo-id2">Click here!</button>';


#css-js-demo-id1 {
color: red;


jQuery(document).ready(function() {

	const params = Joomla.getOptions('my_vars');
	console.log("JS language constant: " + Joomla.JText._('JLIB_HTML_EDIT_MENU_ITEM_ID'));

	var message = Joomla.JText._('JLIB_HTML_EDIT_MENU_ITEM_ID');
	message = message.replace("%s", params.id);
	document.getElementById(params.id).addEventListener("click", function() {alert(message);});

Zip up the mod_css_js_demo directory to create mod_css_js_demo.zip. Within your Joomla Administrator go to Install Extensions and via the Upload Package File tab, select this zip file to install this sample mod_css_js_demo module. Make this module visible by editing it (click on it within the Modules page) then:

  1. making its status Published
  2. selecting a position on the page for it to be shown
  3. on the menu assignment tab specify the pages it should appear on

When you visit the web page, you should see the module in your selected position. It should display:

  • a message Hello World! which the CSS file should change to display in red
  • a button which when you click it will execute an alert() showing the language string and variable which were passed down from the PHP code.

Using your browser's development tools you can also view the <script> and <link> elements within the HTML and see the JavaScript output on the console.