For Bootstrap 4 login form, see this codebank entry: https://www.vbforums.com/showthread....4-0-Login-Form

The code requires the following external files:
  1. Bootstrap 5 CSS - https://getbootstrap.com/


The code uses the following external files, but they are optional:
  1. Font-Awesome 6 - https://fontawesome.com/


HTML:
HTML Code:
<section class="position-relative py-4 py-xl-5">
  <div class="container">
    <div class="row mt-2 mb-3">
      <div class="col-md-8 col-xl-6 text-center mx-auto">
        <h2>Application Name</h2>
        <p class="w-lg-50">Login</p>
      </div>
    </div>
    <div class="row d-flex justify-content-center">
      <div class="col-md-6 col-xl-4">
        <div class="card mb-5">
          <div class="card-body d-flex flex-column align-items-center">
            <div class="my-4">
              <!-- my logo () -->
            </div>
            <form method="post">
              <div class="mb-3">
                <label for="username">Username</label>
                <div class="input-group input-group-extras">
                  <input id="username" class="form-control" name="email" placeholder="Username" autocomplete="username" required />
                  <button class="btn btn-outline-secondary clear-input d-none" type="button">
                    <span class="visually-hidden">Clear</span>
                    <i class="fa-solid fa-x"></i>
                  </button>
                </div>
              </div>
              <div class="mb-3">
                <label for="password">Password</label>
                <div class="input-group input-group-extras">
                  <input type="password" id="password" class="form-control" name="password" placeholder="Password" required />
                  <button class="btn btn-outline-secondary show-password d-none" type="button">
                    <span class="visually-hidden">Show Password</span>
                    <i class="fa-solid fa-eye"></i>
                  </button>
                  <button class="btn btn-outline-secondary hide-password d-none" type="button">
                    <span class="visually-hidden">Hide Password</span>
                    <i class="fa-solid fa-eye-slash"></i>
                  </button>
                  <button class="btn btn-outline-secondary clear-input d-none" type="button">
                    <span class="visually-hidden">Clear</span>
                    <i class="fa-solid fa-x"></i>
                  </button>
                </div>
              </div>
              <div class="mb-3 form-check text-start">
                <input class="form-check-input" type="checkbox" id="specify-domain">
                <label class="form-check-label" for="specify-domain">
                  Specify Domain?
                </label>
              </div>
              <div class="mb-3">
                <button class="btn btn-primary d-block w-100" type="submit">Login</button>
              </div>
            </form>
          </div>
        </div>
      </div>
    </div>
  </div>
</section>
JavaScript:
Code:
// methods
const getSilblingElements = (element) => {
  if (!element) {
    return [];
  }
  
  const parentNode = element.parentNode;
  if(!parentNode) {
    return [];
  }

  const siblings = [];
  let sibling = parentNode.firstChild;
  while (sibling) {
    if (sibling.nodeType === 1 && sibling !== element) {
      siblings.push(sibling);
    }
    sibling = sibling.nextSibling;
  }
  return siblings;
}

const wireUpClearInput = () => {
  const clearInputButtons = document.querySelectorAll('.clear-input');
  for (const clearInputButton of clearInputButtons) {
    const clearInputButtonSiblings = getSilblingElements(clearInputButton);
    const firstInput = clearInputButtonSiblings.find(sibling => sibling.tagName === 'INPUT');
    if (!firstInput) {
      return;
    }
    clearInputButton.addEventListener('mousedown', clearInputButton_Click, false);
    firstInput.addEventListener('input', clearableInput_Change, false);
    firstInput.addEventListener('focusin', clearableInput_Change, false);
    firstInput.addEventListener('focusout', clearableInput_Leave, false);
  }
}

const wireUpHidePassword = () => {
  const hidePasswordButtons = document.querySelectorAll('.hide-password');
  for (const hidePasswordButton of hidePasswordButtons) {
    const hidePasswordButtonSiblings = getSilblingElements(hidePasswordButton);
    const firstInput = hidePasswordButtonSiblings.find(sibling => sibling.tagName === 'INPUT');
    if (!firstInput) {
      return;
    }
    hidePasswordButton.addEventListener('mousedown', hidePasswordButton_Click, false);
    firstInput.addEventListener('input', hidePassword_Change, false);
    firstInput.addEventListener('focusin', hidePassword_Change, false);
    firstInput.addEventListener('focusout', hidePassword_Leave, false);
  }
}

const wireUpShowPassword = () => {
  const showPasswordButtons = document.querySelectorAll('.show-password');
  for (const showPasswordButton of showPasswordButtons) {
    const showPasswordButtonSiblings = getSilblingElements(showPasswordButton);
    const firstInput = showPasswordButtonSiblings.find(sibling => sibling.tagName === 'INPUT');
    if (!firstInput) {
      return;
    }
    showPasswordButton.addEventListener('mousedown', showPasswordButton_Click, false);
    firstInput.addEventListener('input', showPassword_Change, false);
    firstInput.addEventListener('focusin', showPassword_Change, false);
    firstInput.addEventListener('focusout', showPassword_Leave, false);
  }
}

// event handlers
const window_Load = () => {
  wireUpClearInput();
  wireUpHidePassword();
  wireUpShowPassword();
};

const clearableInput_Change = (e) => {
  const element = e.currentTarget;
  const triggeringEvent = element.getAttribute('data-triggering-event') || 'clear-input';
  if (triggeringEvent !== 'clear-input') {
    return;
  }
  element.setAttribute('data-triggering-event', '');
  const siblings = getSilblingElements(element);
  const clearInputDiv = siblings.find(sibling => sibling.classList.contains('clear-input'));
  if (!clearInputDiv) {
    return;
  }
  if (!clearInputDiv.classList.contains('d-none') && !(element.value || element.value.length)) {
    clearInputDiv.classList.add('d-none');
  } else if (clearInputDiv.classList.contains('d-none') && element.value && element.value.length) {
    clearInputDiv.classList.remove('d-none');
  }
};

const clearableInput_Leave = (e) => {
  const element = e.currentTarget;
  const siblings = getSilblingElements(element);
  const clearInputDiv = siblings.find(sibling => sibling.classList.contains('clear-input'));
  if (!clearInputDiv) {
    return;
  }
  if (!clearInputDiv.classList.contains('d-none')) {
    clearInputDiv.classList.add('d-none');
  }
};

const clearInputButton_Click = (e) => {
  const element = e.currentTarget;
  element.setAttribute('data-triggering-event', 'clear-input');
  const clearInputButtonSiblings = getSilblingElements(element);
  const firstInput = clearInputButtonSiblings.find(sibling => sibling.tagName === 'INPUT');
  if (!firstInput) {
    return;
  }
  firstInput.value = '';
};

const hidePassword_Change = (e) => {
  const element = e.currentTarget;
  const triggeringEvent = element.getAttribute('data-triggering-event') || 'hide-password';
  if (triggeringEvent !== 'hide-password') {
    return;
  }
  element.setAttribute('data-triggering-event', '');
  const siblings = getSilblingElements(element);
  const hidePasswordDiv = siblings.find(sibling => sibling.classList.contains('hide-password'));
  if (!hidePasswordDiv) {
    return;
  }
  
  const elementType = element.getAttribute('type');
  if (!hidePasswordDiv.classList.contains('d-none') && (!(element.value || element.value.length) || elementType === 'password')) {
    hidePasswordDiv.classList.add('d-none');
  } else if (hidePasswordDiv.classList.contains('d-none') && element.value && element.value.length && elementType !== 'password') {
    hidePasswordDiv.classList.remove('d-none');
  }
};

const hidePassword_Leave = (e) => {
  const element = e.currentTarget;
  const siblings = getSilblingElements(element);
  const hidePasswordDiv = siblings.find(sibling => sibling.classList.contains('hide-password'));
  if (!hidePasswordDiv) {
    return;
  }
  if (!hidePasswordDiv.classList.contains('d-none')) {
    hidePasswordDiv.classList.add('d-none');
  }
  if (element.getAttribute('type') !== 'password') {
    element.setAttribute('type', 'password');
  }
};

const hidePasswordButton_Click = (e) => {
  const element = e.currentTarget;
  element.setAttribute('data-triggering-event', 'hide-password');
  const hidePasswordButtonSiblings = getSilblingElements(element);
  const firstInput = hidePasswordButtonSiblings.find(sibling => sibling.tagName === 'INPUT');
  if (!firstInput) {
    return;
  }
  e.preventDefault();
  firstInput.setAttribute('type', 'password');
  firstInput.focus();
  firstInput.dispatchEvent(new Event('input', { 'bubbles': true }));
};

const showPassword_Change = (e) => {
  const element = e.currentTarget;
  const triggeringEvent = element.getAttribute('data-triggering-event') || 'show-password';
  if (triggeringEvent !== 'show-password') {
    return;
  }
  element.setAttribute('data-triggering-event', '');
  const siblings = getSilblingElements(element);
  const showPasswordDiv = siblings.find(sibling => sibling.classList.contains('show-password'));
  if (!showPasswordDiv) {
    return;
  }
  
  const elementType = element.getAttribute('type');
  if (!showPasswordDiv.classList.contains('d-none') && (!(element.value || element.value.length) || elementType === 'text')) {
    showPasswordDiv.classList.add('d-none');
  } else if (showPasswordDiv.classList.contains('d-none') && element.value && element.value.length && elementType !== 'text') {
    showPasswordDiv.classList.remove('d-none');
  }
};

const showPassword_Leave = (e) => {
  const element = e.currentTarget;
  const siblings = getSilblingElements(element);
  const showPasswordDiv = siblings.find(sibling => sibling.classList.contains('show-password'));
  if (!showPasswordDiv) {
    return;
  }
  if (!showPasswordDiv.classList.contains('d-none')) {
    showPasswordDiv.classList.add('d-none');
  }
  if (element.getAttribute('type') !== 'password') {
    element.setAttribute('type', 'password');
  }
};

const showPasswordButton_Click = (e) => {
  const element = e.currentTarget;
  element.setAttribute('data-triggering-event', 'show-password');
  const showPasswordButtonSiblings = getSilblingElements(element);
  const firstInput = showPasswordButtonSiblings.find(sibling => sibling.tagName === 'INPUT');
  if (!firstInput) {
    return;
  }
  e.preventDefault();
  firstInput.setAttribute('type', 'text');
  firstInput.focus();
  firstInput.dispatchEvent(new Event('input', { 'bubbles': true }));
};

// window events
window.addEventListener('load', window_Load, false);
Fiddle: https://jsfiddle.net/2xdhuyk1/