Question

How can I add an onchange handler to a dropdown list in Drupal? The dropdown list is added using hook_form(). I have to perform a function depending on the onchange function.
Is there a way to do this?

Answer 1

You can add a form like this:

 hook_form()
 {
   $form1["dropdown"] = array(
    '#type' => 'select',
    '#title' => t('Preview the page with themes available'),
    '#options' => $ptions,
    '#default_value' => 'defalut_value',
    '#attributes' => array('onchange' => "form.submit('dropdown')"),
 );
//Submit button:
$form1['submit'] = array(
    '#type' => 'submit',
    '#value' => t('Submit '),
        '#attributes' => array('style' => 'display: none;'),
);

Now you can add submit functionality using hook_submit().