尝试一下:

$jq('.select-cities').click(function () {
    var zipcodeValue = $jq(this).val();
    //alert(zipcodeValue);
    var oldVal = $jq('.hiddenFieldChosenAreas').val();
    $jq('.hiddenFieldChosenAreas').val(oldVal+"|"+ zipcodeValue);
    $jq('.select-cities option:selected').appendTo('.chosen-cities');
});