当使用angular8单击选项卡时，如何使选项卡聚焦在第一个字段上

Question

嗨，我总共有6个标签，基于一个标签的点击，子标签会打开。子选项卡打开后，我希望焦点位于每个选项卡的第一个子项上。我尝试通过获取第一个标签的ID并尝试在其中获取子标签ID。例如：第一个选项卡是details_basic_info，其子选项卡包含tab-details_basic_info。所以我试图通过添加'tab-'和点击它的动态获取的主标签的ID来使details_basic_info得以获取，但是我未能实现。谁能帮我，这怎么做。

提前感谢。

DEMO：DEMO

Answer 1

[如果是我，我可能会做类似的事情（尽管在方法处理上不那么重复，但是嘿，这只是一个快速的js概念验证，例如与bootstrap一起使用，但是可以很容易地移植到有角度的）您不在乎第一个可聚焦元素是什么，只要它在可聚焦数组中提供即可。

希望这会有所帮助，欢呼！

const focusableList = 'button, [href], input, select, textarea, [tabindex]:not([tabindex="-1"])';

focusFirstFocusableChildPoC = (id) => {

  const contentPane = document.getElementById(id);

  if (contentPane) {
  
      const focusableElements = contentPane.querySelectorAll(focusableList),
            firstFocusable = focusableElements[0];          
            // Typescript will want this to be <HTMLElement>focusableElements[0]; to cast.

      window.setTimeout(function () {
          // Kick this to the back of the line with the 'ol 0 timeout trick.
          firstFocusable ? firstFocusable.focus() : notifyOfFailure();
      }, 0); 
      

  } else {
     notifyOfFailure(); 
  }
}

notifyOfFailure = () => {
  alert('No focus-able element found in specified content, NO FOCUS FOR YOU!');
}

.tab-content {
  padding: 2rem;
}

.tab-content *:focus {
  outline: red 3px solid;
}

.tab-content *:focus:after {
  content: '*';
  margin-top: 1rem;
  color: red;
}

<script src="https://code.jquery.com/jquery-3.3.1.slim.min.js" integrity="sha384-q8i/X+965DzO0rT7abK41JStQIAqVgRVzpbzo5smXKp4YfRvH+8abtTE1Pi6jizo" crossorigin="anonymous"></script>
<script src="https://code.jquery.com/jquery-3.3.1.slim.min.js" integrity="sha384-q8i/X+965DzO0rT7abK41JStQIAqVgRVzpbzo5smXKp4YfRvH+8abtTE1Pi6jizo" crossorigin="anonymous"></script>
<link rel="stylesheet" href="https://stackpath.bootstrapcdn.com/bootstrap/4.3.1/css/bootstrap.min.css" integrity="sha384-ggOyR0iXCbMQv3Xipma34MD+dH/1fQ784/j6cY/iJTQUOhcWr7x9JvoRxT2MZw1T" crossorigin="anonymous">
<script src="https://stackpath.bootstrapcdn.com/bootstrap/4.3.1/js/bootstrap.min.js" integrity="sha384-JjSmVgyd0p3pXB1rRibZUAYoIIy6OrQ6VrjIEaFf/nJGzIxFDsf4x0xIM+B07jRM" crossorigin="anonymous"></script>


<ul class="nav nav-tabs" id="myTab" role="tablist">
  <li class="nav-item">
    <a class="nav-link active" data-toggle="tab" href="#panel1" role="tab" onclick="focusFirstFocusableChildPoC('panel1')">Home</a>
  </li>
  <li class="nav-item">
    <a class="nav-link" data-toggle="tab" href="#panel2" role="tab" onclick="focusFirstFocusableChildPoC('panel2')">Profile</a>
  </li>
  <li class="nav-item">
    <a class="nav-link" data-toggle="tab" href="#panel3" role="tab" onclick="focusFirstFocusableChildPoC('panel3')">Contact</a>
  </li>
  <li class="nav-item">
    <a class="nav-link" data-toggle="tab" href="#panel4" role="tab" onclick="focusFirstFocusableChildPoC('panel4')">Contact</a>
  </li>
  <li class="nav-item">
    <a class="nav-link" data-toggle="tab" href="#panel5" role="tab" onclick="focusFirstFocusableChildPoC('panel5')">Contact</a>
  </li>
</ul>

<div class="tab-content" id="myTabContent">
  <div class="tab-pane show active" id="panel1" role="tabpanel">
    <input placeholder="a text input" type="text">
    <button>A Button</button>
    <input type="checkbox">
    <input type="number">
  </div>
  <div class="tab-pane" id="panel2" role="tabpanel">
    <label><input type="checkbox"> Focus testing</label>
    <input type="text">
    <button>A Button</button>
    <input type="number">
  </div>
  <div class="tab-pane" id="panel3" role="tabpanel">
    <button>A Button</button>
    <input type="text">
    <input type="checkbox">
    <input type="number">
  </div>
  <div class="tab-pane" id="panel4" role="tabpanel">
    <a href="#">Test Anchor Link</a>
    <button>A Button</button>
    <input type="text">
    <input type="checkbox">
    <input type="number">
  </div>
  <div class="tab-pane" id="panel5" role="tabpanel">
    Nothing here to focus bro...
  </div>
</div>