<select name="travel[]" id="travel[]"  >
     <option   value="1">Car</option>
<select>
<select name="travel[]" id="travel[]"  >
     <option   value="2">Train</option>
<select>
<select name="travel[]" id="travel[]"  >
     <option   value="3">Bus</option>
<select>

var data = $('select[name="travel[]"]').map(function () {
    return $(this).val();
}).get();

console.log(data);    // ["1", "2", "3"]

<select name="travel" id="select_travel">
     <option value="1">Car</option>
     <option value="2">Train</option>
     <option value="3">Bus</option>
<select>

$('#select_travel').val();

<select name="travel[]" id="abc">
  </select>

  <select name="travel[]" id="def">
  </select>

  <select name="travel[]" id="xyz">
  </select>

$("#abc").val();
   $("#def").val();
   $("#xyz").val();

<select name="travel[]" id="travel[]" class="abc">
  </select>

  <select name="travel[]" id="travel[]" class="xyz">
  </select>

$(".abc").val();
   $(".xyz").val();

var selectOption=$('#select_travel').val()
var Id=selectOption.getAttribute('id');
var name=selectOption.getgetAttribute('id');