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Version: 4.4

Joomla core.js

Provides a global Joomla object and a core functionality for client side: options storage, translations, etc.

To enable it on the page use WebAssetManager $wa->useScript('core').

Client side options

Joomla provides a generic way to share script options between server side and client side. To share your script option from php to javascript, add them:

$doc = Joomla\CMS\Factory::getApplication()->getDocument();
$doc->addScriptOptions('my_extension_options', ['foo' => 'bar']);

To read the options on client side:


Client side translations

To add translation to your script, add needed strings in a layout:


Use in your script:

console.log(Joomla.Text('LANG_CONSTANT1', 'Default string1'));
console.log(Joomla.Text('LANG_CONSTANT2', 'Default string2'));
console.log(Joomla.Text('LANG_CONSTANT3', 'Default string3'));

Note: Fallback to default string works only when the language constant was not added at all. When it was added but untranslated then it will return untranslated constant.

Sanitize Html string

Joomla.sanitizeHtml() method sanitize untrusted HTML string. And should be used anytime when rendering HTML that comes from dynamic variables, translations etc.

const myElement = document.createElement('div');
myElement.innerHTML = Joomla.sanitizeHtml(Joomla.Text('LANG_CONSTANT1', '<p>Default string1</p>'));

Joomla ajax request

For basic stuff like simple GET requests it is recommended to use browser native fetch() method. However, when need something more complex, like Upload with progress, or queue requests, Joomla provide Joomla.request() method. Which is a wrapper around XMLHttpRequest



  • url: '' Request URL
  • method: 'GET' Request method GET (default), POST etc.
  • data Data to be sent, see
  • promise: false Whether return a Promise instance. When is true then next options are ignored: perform, onSuccess, onError, onComplete.
  • perform: true Perform the request immediately or return XMLHttpRequest instance and perform it later.
  • headers: {} Object of custom headers, eg {'X-Foo': 'Bar', 'X-Bar': 'Foo'}.
  • onBefore: (xhr) => {} Callback on before the request
  • onSuccess: (response, xhr) => {} Callback on the request success
  • onError: (xhr) => {} Callback on the request error
  • onComplete: (xhr) => {} Callback on the request completed, with/without error

Example upload:

const formData = new FormData;
formData.append('file', fileBlob, filename);

url: 'index.php?option=com_example&task=upload.file',
method: 'POST',
promise: true,
data: formData,
onBefore(xhr) {
xhr.upload.addEventListener('progress', (event) => {
console.log('Progres', event.loaded,;
}).then((xhr) => {
console.log('File uploaded');
}).catch((error) => {
console.log('File failed');


A FIFO queue of requests to execute serially. Used to prevent simultaneous execution of multiple requests against the server which could trigger its Denial of Service protection. Accepts the same options as Joomla.request(), with one difference, it requires promise to be set to true.

Example queue: