使用jquery添加属性以输入数据验证

Question

我有一个选择字段

<select data-validation="required" class="form-control error" id="femanager_field_usergroup" name="tx_femanager_pi1[user][usergroup][0]">
<option value="">Bitte wählen...</option> 
<option value="2">Mitglied</option>
<option value="5">Nicht-Mitglied</option> 

和

<div class="femanager_fieldset femanager_title form-group"> <label for="femanager_field_title" class="col-sm-2 control-label"> Mitgliedsnummer </label> 
<div class="col-sm-10"> <input data-validation="mustNotInclude(letter|special|space)" class="form-control" id="femanager_field_title" name="tx_femanager_pi1[user][title]" type="text"> </div>
</div>

根据我显示或隐藏的选定选项 .femanager_title 用jquery

$(function () {
$(".femanager_title").hide();
$("#femanager_field_usergroup").change(function() {
    var val = $(this).val();
    if(val === "2") {
        $(".femanager_title").slideDown( "slow" );
    }
    else {
        $(".femanager_title").slideUp( "slow" );
    }
  });
});

如何添加＆＃39; required＆＃39;到数据验证＆＃39;如果.femanager_title 显示？

我想要

<input data-validation="required,mustNotInclude(letter|special|space)" class="form-control error" id="femanager_field_title" name="tx_femanager_pi1[user][title]" type="text">