Question

how could i do: if in #myselect1 volvo is selected then remove 1st(740) and 2nd(940) option in #myselectVolvo

<select id="myselect1">
  <option value="volvo">Volvo</option>
  <option value="saab">Saab</option>
  <option value="mercedes">Mercedes</option>
  <option value="audi">Audi</option>
</select>

<select id="myselectVolvo">
  <option value="740">740</option>
  <option value="940">940</option>
  <option value="240">240</option>
  <option value="340">340</option>
</select>

Answer 1

$('#myselect1').change(function(){
  if($(this).val() == 'volvo'){ // or this.value == 'volvo'
    $('#myselectVolvo option:lt(2)').remove();
  }
});