如何在没有value属性的情况下获取输入类型的值

Question

我对此感到困惑。我有这样的HTML文件：

$(document).ready(function() {
  $('select.supplier').change(function() {
    var capacityValue = $('select.supplier').find(':selected').data('capacity');
    $('.supplierCapacity').val(capacityValue);
  });
});

$(document).ready(function() {
  $('select.supplier').change(function() {
    var countryValue = $('select.supplier').find(':selected').data('country');
    $('.supplierCountry').val(countryValue);
  });
});

select,
input {
  padding: 5px;
  margin: 5px 0 10px;
  font-weight: bold;
}

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
Choose Supplier :
<br>
<form method="post" action="submit.php">
  <select class="supplier" name="supplier">
    <option data-country="Argentine" data-capacity="100" value="10">Johny Farms</option>
    <option data-country="Belgium" data-capacity="200" value="20>">Jack & Jane Farms</option>
    <option data-country="Canada" data-capacity="300" value="30">Crabs Crane</option>
  </select><br>

  <input type="hidden" name="supplierCapacity" class="supplierCapacity" readonly /><br>
  Country :<br>
  <input type="text" name="supplierCountry" class="supplierCountry" readonly /><br>
  <input type="submit" value=" save ">
</form>

如何获取要发布的输入值。我在submit.php中编写了这段代码但不起作用：

$capacity = $_POST['supplierCapacity'];
$country = $_POST['supplierCountry'];

Answer 1

为输入添加ID

<input id="testing"  />

在javascript中，获取输入值

document.getElementId('testing').value

或

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