为什么这个jQuery'最接近'的代码不起作用？

Question

当我点击“生成”按钮时，我希望根据代码生成#payment_reference字段值。我认为代码很清楚我想要它做什么，但由于某种原因它不起作用：（

我添加了alert用于测试目的，但它只输出undefined

$( document ).ready(function() {
// generate payment reference

$( "#generate_payment_reference" ).click(function() {
    $( ".amount_received" ).each(function( index ) {
		var thisAmount = parseFloat($(this).val());
		var paymentRef = '';
        if (thisAmount > 0) {
            paymentRef += $(this).closest(".invoice_reference").val();
			alert($(this).closest(".invoice_reference").val());
        }
		$('#payment_reference').val(paymentRef);
    });
});
});

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.0.0/jquery.min.js"></script>
<fieldset>
  <legend>Client Details</legend>

  <table class="nobord">
    <tr>
      <td>Type:</td>
      <td>Landlord </td>
    </tr>
    <tr>
      <td>Name:</td>
      <td>Mr XXX</td>
    </tr>
    <tr>
      <td>Client Bank Account Balance:</td>
      <td>&pound;387.68</td>
    </tr>
  </table>

</fieldset>
<fieldset>
  <legend>Outstanding Invoice Details</legend>
  <table class="solid" style="margin:5px;">
    <tr>
      <th>Invoice #</th>
      <th>Date</th>
      <th>Due Date</th>
      <th>Invoice Total</th>
      <th>Amount Paid</th>
      <th>Amount Due</th>
      <th>Amount Received (&pound;)</th>
    </tr>
    <tr>
      <td><a href="view_invoice.php?invoice_id=496" target="_blank">496</a>
        <input type="text" class="invoice_reference" value="496">
      </td>
      <td>14/01/16</td>
      <td>14/01/16</td>
      <td>&pound;25.20</td>
      <td>&pound;0.00</td>
      <td>&pound;25.20
        <input type="hidden" name="amount_outstanding[]" value="25.20">
      </td>
      <td>
        <input type="number" name="amount_received[]" class="amount_received" value="0.00" max="25.20" required>&nbsp;
        <button class="pay_in_full" type="button">Pay in Full</button>
        <input type="hidden" name="invoice_id[]" value="496">
        <input type="hidden" name="invoice_tenancy_id[]" value="40">
        <input type="hidden" name="invoice_property_id[]" value="119">
      </td>
    </tr>
    <tr>
      <td><a href="view_invoice.php?invoice_id=497" target="_blank">497</a>
        <input type="text" class="invoice_reference" value="497">
      </td>
      <td>14/01/16</td>
      <td>14/01/16</td>
      <td>&pound;25.20</td>
      <td>&pound;0.00</td>
      <td>&pound;25.20
        <input type="hidden" name="amount_outstanding[]" value="25.20">
      </td>
      <td>
        <input type="number" name="amount_received[]" class="amount_received" value="0.00" max="25.20" required>&nbsp;
        <button class="pay_in_full" type="button">Pay in Full</button>
        <input type="hidden" name="invoice_id[]" value="497">
        <input type="hidden" name="invoice_tenancy_id[]" value="40">
        <input type="hidden" name="invoice_property_id[]" value="119">
      </td>
      </td>
    </tr>
  </table>
</fieldset>
<fieldset>
  <legend>Payment Details</legend>

  <table class="nobord">
    <tr>
      <td>
        <label for="invoice_payment_date">Date:</label>
      </td>
      <td>
        <input type="date" id="invoice_payment_date" name="invoice_payment_date" class="datepicker2months" ondblclick="this.value='2016-01-14';" readonly required>
      </td>
    </tr>
    <tr>
      <td>
        <label for="total_amount_received">Total Amount Received (&pound;):</label>
      </td>
      <td>
        <input type="number" id="total_amount_received" name="total_amount_received" readonly required>
        <input type="hidden" id="client_bank_account_balance" name="client_bank_account_balance" value="387.68" required>
      </td>
    </tr>
    <tr>
      <td>
        <label for="payment_reference">Payment Reference:</label>
      </td>
      <td>
        <input type="text" id="payment_reference" readonly>&nbsp;
        <button id="generate_payment_reference" type="button">Generate</button>
      </td>
    </tr>
    <tr>
      <td>
        <label for="invoice_payment_use_balance">Pay from Client Bank Account Balance:</label>
      </td>
      <td>
        <select id="invoice_payment_use_balance" name="invoice_payment_use_balance" required>
          <option value="">Please Select</option>
          <option value="0">No</option>
          <option value="1" selected>Yes</option>
        </select>
      </td>
    </tr>
    <tr>
      <td>
        <label for="invoice_payment_method">Method:</label>
      </td>
      <td>
        <select id="invoice_payment_method" name="invoice_payment_method" required>
          <option value="">Please Select</option>
          <option value="2" selected>Bank Transfer</option>
          <option value="1">Cash</option>
          <option value="3">Cheque</option>
          <option value="4">Credit Card</option>
          <option value="5">Debit Card</option>
        </select>
      </td>
    </tr>
    <tr>
      <td>
        <label for="invoice_payment_notes">Notes:</label>
      </td>
      <td>
        <textarea id="invoice_payment_notes" name="invoice_payment_notes" rows="6" cols="40"></textarea>
      </td>
    </tr>
  </table>

</fieldset>

Answer 1

这是因为您的.invoice_reference元素不是.amount_received元素的祖先。相反，您可以前往tr元素并使用find()来提取.invoice_reference内的$(this).closest('tr').find(".invoice_reference").val() ：

export EDITOR=nano
sudo -E crontab -e

Answer 2

如果$(".amount_received").length等于$(".invoice_reference").length，请尝试使用带有参数.eq()的{​​{1}};将index移到$('#payment_reference').val(paymentRef);之外，使其不被覆盖。请注意，在.each()处重复关闭</td>。

另请注意，不确定的是，预期结果是串联字符串还是html变量中的值的添加？

paymentRef

$( document ).ready(function() {
// generate payment reference

$( "#generate_payment_reference" ).click(function() {
  var paymentRef = "";
    $( ".amount_received" ).each(function( index ) {
		var thisAmount = parseFloat($(this).val());
		//var paymentRef = '';
        if (thisAmount > 0) {
            paymentRef += $(".invoice_reference").eq(index).val();
        }
		
    });
  $('#payment_reference').val(paymentRef);
});
});