在drupal 7 forms api中的SelectForm控件中触发onchange事件

我在Drupal7中有一个选择表单控件。如何在onchange事件触发时调用函数

这是我的选择表单控制代码：

$form['id']['signature'] = array(
    '#type' => 'select',       
    '#options' => array(
        0 => t('Browse...'),
        1 => t('Sign...'),
        2 => t('Clear...'),        
    ),       
);

---

你可以用“attibutes”来做这件事。
例如

虽然我从不喜欢将事件属性添加到html标记中，但您也可以通过向表单中添加内联（或扩展）javascript来实现，其行为如下：

$form['id']['signature'] = array(
    '#type' => 'select',       
    '#options' => array(
        0 => t('Browse...'),
        1 => t('Sign...'),
        2 => t('Clear...'),        
    ),
    '#attributes' => array(
        'id' => array('signature-goes-here'),
    ),
);
$form['id']['signature']['#attached']['js'][] = array(
    'data' => "
Drupal.behaviors.signature = function (context) {
  $('#signature-goes-here', context).change(function () {
    // Do stuff here.
  });
}
",
    'type' => 'inline',
);

但是，如果您想在表单项发生变化时启动ajax，您可能会使用Drupal表单api功能

$form['id']['signature'] = array(
    '#type' => 'select',       
    '#options' => array(
        0 => t('Browse...'),
        1 => t('Sign...'),
        2 => t('Clear...'),        
    ),
    '#attributes' => array(
        'id' => array('signature-goes-here'),
    ),
);
$form['id']['signature']['#attached']['js'][] = array(
    'data' => "
Drupal.behaviors.signature = function (context) {
  $('#signature-goes-here', context).change(function () {
    // Do stuff here.
  });
}
",
    'type' => 'inline',
);