How to get the tab focus on the first field when the tab is clicked using angular8

Question

Hi i have totally 6 tabs, based on click of one tab the sub tabs opens. As soon as the subtab opens i want the focus to be on the first child of every tab. I tried by taking the id of first tab and trying to fetch the subtab id in that. For example: 1st tab is details_basic_info its sub tab contains tab-details_basic_info. So i tried to make details_basic_info to fetched and based on this by adding 'tab-' with the id of the dynamically fetched main tab on which it is clicked.But i failed to implement. can anyone help me out, how this can be done.

Thanks in advance.

DEMO: DEMO

Answer 1

If it were me I'd probably do something like this (although a bit less repetitive with the method handling but hey it's just a quick vanilla js proof of concept slapped together with bootstrap for example but can easily be ported to angular) so you don't care what the first focus-able element is as long it's supplied in the array that can be focused.

Hope this helps, cheers!

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 FOR YOU!');
}

.tab-content {
  padding: 2rem;
}

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

.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>