anchor.diff:                </span>
               </button>
             </span>
  +        </div>
  +        <div class="text-danger small" ng-if="mandatureForm.birthdate.$invalid">
  +          Not a valid date format (use YYYY-MM-DD).
           </div>
         </div>
         <div class="col-xs-4 mandature-form__group__helper">
  
positive.code:         <div class="input-group">
            <input class="form-control"
                   flatpickr
                   data-dateFormat="Y/m/d"
                   type="text"
                   ng-model="form.mandature.person.birthdate"
                   id="input-birthdate" />
            <span class="input-group-btn">
              <button class="btn btn-secondary" ng-click="form.editSource('birthdate', form.mandature.person)" type="button">
  
negative.code: <form ng-submit="form.submit()" name="mandatureForm">
  
    <div class="mandature-form card-block">
  
  