Drupal - Simple confirmation popup dialog box

I got it!!!

Here's a simple 100% functioning exmple:

$form['delete'] = array(
    '#type' => 'submit',
    '#value' => t('Delete'),
    '#attributes' => array('onclick' => 'if(!confirm("Really Delete?")){return false;}'),
);

I hope this helps.

Happy coding :)

Drupal has a native confirm_form() function, but it is server side rather than Javascript based, which is what I assume you mean.