Invoke custom JS function in AJAX callback?

Question

Is it possible to invoke a custom JS function in an AJAX callback?

function MY_MODULE_ajax_callback() {
  // Define a new array to hold our AJAX commands.
  $ajax_commands = array();

  // Create a new AJAX command that replaces the #page text with our own text.
  $ajax_commands[] = [CUSTOM JS FUNCTION]

  // Return our commandS
  return array('#type' => 'ajax','#commands' => $commands);
}

Answer 1

You can't run an arbitrary script, but if you can wrap your JS functionality in a jQuery plugin you can use ajax_command_invoke to get the same effect, e.g.

$selector = 'body';
$method = 'myJqueryPlugin';
$args = array('arg1', 'arg2');

$ajax_commands[] = ajax_command_invoke($selector, $method, $args);

When that comes out in the front end it'll execute something equivalent to

$('body').myJqueryPlugin('arg1', 'arg2');

Answer 2

Yes, it is.

Code sample:

$commands = array();
$commands[] = array(
    'command' => 'your_js_callback', // the name of your javascript callback
    'value1'  => 'My first value',
    'value2'  => 'My second value',
);

JS Code:

(function($, Drupal) {
    Drupal.ajax.prototype.commands.your_js_callback = function(ajax, response, status) {
        alert(response.value1);
        alert(response.value2);
    }
})(jQuery, Drupal);