javascript - 无法获取元素的值

Question

我正在尝试获取输入元素的值。该元素位于模态中，并且模态数据填充有不同的值，具体取决于我单击打开模态的按钮。

var modalBody = document.getElementsByClassName("modal-body");
for(var i = 0; i < modalbody.length; i++) {
    var mac = modalBody.item(i).getElementsByTagName('div')[2].getElementById("mac-name").value;
    alert(mac);
}

error: TypeError: modalBody.item(...).getElementsByTagName(...)[2].getElementById is not a function

我还尝试了 document.getElementById("mac-name").value; 但返回空白

<form method="post">
    <div class="modal-body">
        <div class="form-group">
            <label for="station-name" class="col-form-label">ID:</label>
            <input class="form-control" id="station-id" name="edit--id" required="" type="text" hidden="">
            <input class="form-control" id="station-name" name="edit--name" required="" type="text">
        </div>
        <div class="form-group">
            <label for="profile-name" class="col-form-label">Profile:</label>
            <select type="text" class="form-control" id="profile-name" name="edit-profile" required="">
            <option>name1</option>
            <option>name2</option>
            </select>
        </div>
        <div class="form-group">
            <label for="mac-name" class="col-form-label">MAC Address:</label>
            <input class="form-control" id="mac-name" name="edit-mac" required="" type="text">
        </div>
    </div>
</form>

Answer 1

而不是使用 getElementsByClassName 然后在每个元素上运行以下命令:

var mac = modalBody.item(i).getElementsByTagName('div')[2].getElementById("mac-name").value;

您可以使用 querySelectorAll 并传入 .modal-body div #mac-name。这将选择类 modal-body 元素内 div 内具有 id mac-name 的所有元素。您可以使用此结果循环遍历每个元素并获取每个值:

var macs = document.querySelectorAll('.modal-body div #mac-name');

参见下面的示例:

var macs = document.querySelectorAll('.modal-body div #mac-name');
for (var i = 0; i <  macs.length; i++) {
  var mac = macs[i].value;
  console.log(mac);
}

<form method="post">
  <div class="modal-body">
    <div class="form-group">
      <label for="station-name" class="col-form-label">ID:</label>
      <input class="form-control" id="station-id1" name="edit--id" required="" type="text" hidden="">
      <input class="form-control" id="station-name1" name="edit--name" required="" type="text">
    </div>
    <div class="form-group">
      <label for="profile-name" class="col-form-label">Profile:</label>
      <select type="text" class="form-control" id="profile-name1" name="edit-profile" required="">
        <option>name1</option>
        <option>name2</option>
      </select>
    </div>
    <div class="form-group">
      <label for="mac-name" class="col-form-label">MAC Address:</label>
      <input class="form-control" id="mac-name" name="edit-mac" value="Addr 1" required="" type="text">
    </div>
  </div>
  
  <div class="modal-body">
    <div class="form-group">
      <label for="station-name" class="col-form-label">ID:</label>
      <input class="form-control" id="station-id2" name="edit--id" required="" type="text" hidden="">
      <input class="form-control" id="station-name2" name="edit--name" required="" type="text">
    </div>
    <div class="form-group">
      <label for="profile-name" class="col-form-label">Profile:</label>
      <select type="text" class="form-control" id="profile-name2" name="edit-profile" required="">
        <option>name1</option>
        <option>name2</option>
      </select>
    </div>
    <div class="form-group">
      <label for="mac-name" class="col-form-label">MAC Address:</label>
      <input class="form-control" id="mac-name" name="edit-mac" value="Addr 2" required="" type="text">
    </div>
  </div>
</form>