javascript - 如何反转两个输入选择之间的选项值？

Question

我有两个输入选择，具有相同的选项。当我单击触发器时，我需要反转这两个选择之间的选项值。例如:

<select id="source_currency">
 <option value="BRL" selected>BRL</option>
 <option value="USD">USD</option>
 <option value="EUR">EUR</option>
</select>

<select id="target_currency">
 <option value="BRL">BRL</option>
 <option value="USD">USD</option>
 <option value="EUR" selected>EUR</option>
</select>

我需要的是，点击触发器会发生这样的情况:

<select id="source_currency">
 <option value="BRL">BRL</option>
 <option value="USD">USD</option>
 <option value="EUR" selected>EUR</option>
</select>

<select id="target_currency">
 <option value="BRL" selected>BRL</option>
 <option value="USD">USD</option>
 <option value="EUR">EUR</option>
</select>

我想用这样的函数更改值(但不起作用):

<a href="#" class="is-txt-green-light" id="invertConvert">Invert</a>

// JS
function invertCurrency() {
  let sourceCurrency = $('#source_currency');
  let targetCurrency = $('#target_currency');
  const triggerInvert = $('#invertConvert');

  triggerInvert.click((e) => {
    e.preventDefault();
    sourceCurrency.val(targetCurrency.val())
  })
}

我怎样才能做到这一点？谢谢!

Answer 1

如果您尝试像这样交换字段的值:

当用户单击“反转”按钮时，字段的值会交换。

const triggerInvert = $('#invertConvert');

triggerInvert.click((e) => {
  let sourceCurrency = $('#source_currency');
  let sourceCurrency_val = sourceCurrency.val();

  let targetCurrency = $('#target_currency');
  let targetCurrency_val = targetCurrency.val();

  e.preventDefault();
  sourceCurrency.val(targetCurrency_val);
  targetCurrency.val(sourceCurrency_val);
})

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<select id="source_currency">
  <option value="GBP" selected>Pound Sterling</option>
  <option value="USD">Dollar</option>
  <option value="EUR">Euro</option>
</select>

<select id="target_currency">
  <option value="GBP">Pound Sterling</option>
  <option value="USD">Dollar</option>
  <option value="EUR" selected>Euro</option>
</select>

<button id="invertConvert">
Convert
</button>