$(document).ready(function(){

   var prefixNumber = $('.numeric').val();

   if(prefixNumber.match(????){
      prefixNumber.addClass('.field-error');
   }

});

$('.numeric').change(function () {
    $(this).toggleClass('field-error', /[^0-9]/.test(this.value));
});

var valid = {
   1: true,
   3: true,
   8: true,
   999: true
};

var timer = null;

function validate() {
     var val = $('.numeric').val()
     $('.numeric').toggleClass('field-error',  val !=='' && !valid[+val]);
}

$('.numeric').keyup(function() {
    clearTimeout(timer);
    setTimeout(validate, 400); // time has to be adjusted...
});

$(document).ready(function(){

   var prefixNumber = $('.numeric');

   if(!prefixNumber.val().match(/^(1|3|8)$/){
      prefixNumber.addClass('field-error');
   }

});