jquery how to hide the select arrow when the ajax return only one option

well, just note it for memo.
html:

less:

/* Select arrow styling */
.address_city_chooser{
    >div{
        position:relative;
        display:inline-block;
        &.disabled{
            label:after{
                content: '';
                width: 23px;
                height: 23px;
                position: absolute;
                display: inline-block;
                top: 4px;
                right: 4px;
                background:  #fff;
                pointer-events: none;
            }
        }
    }
}

and js:

  

                 $.get(
   Routing.generate('prospection_public_city',{'postCode':code,'_locale':currentLang}),
   function(response){
   if(typeof response.error!="undefined"){
    $('#errorDialog').html(response.error);
    $('#errorDialog').dialog('open');
   }else{
    $(container).html(response);
    if ($(container).find('option').length<2){
     $(container).prop('disabled', 'disabled');
     $(container).closest('div').addClass('disabled');
    }else{
     $(container).prop('disabled', false);
     $(container).closest('div').removeClass('disabled');
    }
     
     
    //what ever we set the first in select.
    var postcodeRadio=$(container).closest('.address_city_chooser').find('.address_city input');
    //set the submit value
    $(postcodeRadio).val($('option:selected', container).val());
   }
  });