jQuery将数据从一个字段发送到另一字段

Question

仅当字段中有数据时，我才尝试将数据从一个字段推到另一字段。如果Requeter_UserName_COAS中有数据，那么我希望将该数据推送到Requester_UserName字段。这是我对字段集（文本字段）的代码，对帮助onchange函数有什么建议吗？

    $form['fieldform']['coas']['Requester_UserName_COAS'] = array(
    '#type' => 'textfield',
    '#title' => t('Faculty Name'),
    '#required' => TRUE,
    '#attributes' => array( 'placeholder' => "Alex Jones",
         'required' => "required",
            ),
    '#prefix' => '<div class="forms-jd">',
    '#suffix' => '</div>',

    'onchange' => "if($(this).val() = True)  {this.form.elements['Requester_UserName'].value = 'Requester_UserName_COAS';}",