Sending a value to JavaScript

Question

I have set theme handler for a form in Drupal and this handler has a template file. What is the easiest way to send a value from PHP to JavaScript in that include file?

Answer 1

The standard way to do this in Drupal is with drupal_add_js, using the "setting" type:

drupal_add_js(array('variableName' => 'value'), 'setting');

That will make the variable available on the JS side at Drupal.settings.variableName.

Answer 2

Few more examples on drupal_add_js,

It's better to specify your module name while adding JS variable to avoid any issues,

drupal_add_js(array('myModule' => array('key' => 'value')), 'setting');

In case you want to execute some JS code after the DOM is initialized,

drupal_add_js('jQuery(document).ready(function () { alert("Hello!"); });', 'inline');

Answer 3

Also, the #attached key to a form can be used for sending php variable to js.

  $my_variable = 'My custom value';
  $form['some-element']['#attached']['js'] = array(
    array(
     'data' => drupal_get_path('module', 'my_module') . '/js/script.js',
    ),
    array(
      'data' => array(
        'variable' => $my_variable,
       ),
      'type' => 'setting',
    ),
  );

This can be used in hook_form_alter for example.

Answer 4

Easiest way is just to echo it out into a script tag:

<script type="text/javascript">
   var variableName = <?php echo $variable ?>;
</script>

If Drupal uses a templating language, you need to replace the <?php echo... ?> with the relevent output method...