Индикатор прокрутки в модале начальной загрузки

Question

Я пытаюсь вычислить индикатор прокрутки в модальном окне начальной загрузки.

Я могу правильно рассчитать для прокрутки окна.Тем не менее, расчет не является правильным внутри прокрутки модального поля.Пожалуйста, помогите мне.

$('.modal-body').scroll(function () {
  var scroll = $('.modal-body').scrollTop(),
        modalHeight = $('#exampleModalLong').height(),
        contantHeight = $('.modal-body').height();
       scrollPercent = ((scroll / (modalHeight-contantHeight)) * 100);
        var position = scrollPercent;
        var width = position+'%';

   $("#progressbar").attr('aria-valuenow', position);
   $("#progressbar").css('width', width);

   console.log('scroll is ' + scroll);
   console.log('modalHeight is ' + modalHeight);
   console.log('contantHeight is ' + contantHeight);
   console.log('width is ' + position);

});

.modal-content{
   max-height: calc(100vh - 100px);
}
.modal-body{ 
  overflow-y: auto;
}

<link rel="stylesheet" type="text/css" href="https://stackpath.bootstrapcdn.com/bootstrap/4.2.1/css/bootstrap.min.css">
<script src="https://code.jquery.com/jquery-3.3.1.min.js" integrity="sha256-FgpCb/KJQlLNfOu91ta32o/NMZxltwRo8QtmkMRdAu8=" crossorigin="anonymous"></script>
<script type="text/javascript" src="https://stackpath.bootstrapcdn.com/bootstrap/4.2.1/js/bootstrap.min.js"></script>

<!-- Button trigger modal -->
<button type="button" class="btn btn-primary" data-toggle="modal" data-target="#exampleModalLong">
  Launch demo modal
</button>

<!-- Modal -->
<div class="modal fade" id="exampleModalLong" tabindex="-1" role="dialog" aria-labelledby="exampleModalLongTitle" aria-hidden="true">
  <div class="modal-dialog" role="document">
    <div class="modal-content">
      <div class="modal-header">
        <h5 class="modal-title" id="exampleModalLongTitle">Modal title</h5>
        <button type="button" class="close" data-dismiss="modal" aria-label="Close">
          <span aria-hidden="true">&times;</span>
        </button>
      </div>
      <div class="progress">
				<div id="progressbar" class="progress-bar" role="progressbar" aria-valuenow="0" aria-valuemin="0" aria-valuemax="100"></div>
			</div>
      <div class="modal-body">
        Cras mattis consectetur purus sit amet fermentum. Cras justo odio, dapibus ac facilisis in, egestas eget quam. Morbi leo risus, porta ac consectetur ac, vestibulum at eros. Praesent commodo cursus magna, vel scelerisque nisl consectetur et. Vivamus sagittis
        lacus vel augue laoreet rutrum faucibus dolor auctor. Aenean lacinia bibendum nulla sed consectetur. Praesent commodo cursus magna, vel scelerisque nisl consectetur et. Donec sed odio dui. Donec ullamcorper nulla non metus auctor fringilla. Cras
        mattis consectetur purus sit amet fermentum. Cras justo odio, dapibus ac facilisis in, egestas eget quam. Morbi leo risus, porta ac consectetur ac, vestibulum at eros. Praesent commodo cursus magna, vel scelerisque nisl consectetur et. Vivamus
        
        sagittis lacus vel augue laoreet rutrum faucibus dolor auctor. Aenean lacinia bibendum nulla sed consectetur. Praesent commodo cursus magna, vel scelerisque nisl consectetur et. Donec sed odio dui. Donec ullamcorper nulla non metus auctor fringilla.
        Cras mattis consectetur purus sit amet fermentum. Cras justo odio, dapibus ac facilisis in, egestas eget quam. Morbi leo risus, porta ac consectetur ac, vestibulum at eros. Praesent commodo cursus magna, vel scelerisque nisl consectetur et. Vivamus
        sagittis lacus vel augue laoreet rutrum faucibus dolor auctor. Aenean lacinia bibendum nulla sed consectetur. Praesent commodo cursus magna, vel scelerisque nisl consectetur et. Donec sed odio dui. Donec ullamcorper nulla non metus auctor fringilla.
          sagittis lacus vel augue laoreet rutrum faucibus dolor auctor. Aenean lacinia bibendum nulla sed consectetur. Praesent commodo cursus magna, vel scelerisque nisl consectetur et. Donec sed odio dui. Donec ullamcorper nulla non metus auctor fringilla.
        Cras mattis consectetur purus sit amet fermentum. Cras justo odio, dapibus ac facilisis in, egestas eget quam. Morbi leo risus, porta ac consectetur ac, vestibulum at eros. Praesent commodo cursus magna, vel scelerisque nisl consectetur et. Vivamus
        sagittis lacus vel augue laoreet rutrum faucibus dolor auctor. Aenean lacinia bibendum nulla sed consectetur. Praesent commodo cursus magna, vel scelerisque nisl consectetur et. Donec sed odio dui. Donec ullamcorper nulla non metus auctor fringilla.
        
      </div>
      <div class="modal-footer">
        <button type="button" class="btn btn-secondary" data-dismiss="modal">Close</button>
        <button type="button" class="btn btn-primary">Save changes</button>
      </div>
    </div>
  </div>
</div>

Я хочу, чтобы значение ширины составляло 100 при прокрутке вниз до нижнего конца.

Answer 1

Вы можете использовать ванильное свойство JS элемента .scrollHeight, чтобы получить общую высоту прокрутки.Вычтите из этого видимую высоту элементов, которую вы можете получить с помощью функции jQuery innerHeight(), и у вас будет общая прокручиваемая высота.Затем просто поделите на позицию прокрутки, как вы ее кодировали.

$('.modal').modal();

$('.modal-body').scroll(function() {
  const scrollBox = $('.modal-body'),
    scroll = scrollBox.scrollTop(),
    scrollHeight = scrollBox[0].scrollHeight,
    containerHeight = scrollBox.innerHeight();
  scrollPercent = (scroll / (scrollHeight - containerHeight) * 100);

  $("#progressbar").attr('aria-valuenow', scrollPercent);
  $("#progressbar").css('width', scrollPercent + '%');

  console.log('scroll is ' + scroll);
  console.log('scrollPercent is ' + scrollPercent);

});

.modal-body {
  height: 150px;
  overflow-y: auto;
}

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<script src="https://stackpath.bootstrapcdn.com/bootstrap/4.2.1/js/bootstrap.bundle.min.js"></script>
<link href="https://stackpath.bootstrapcdn.com/bootstrap/4.2.1/css/bootstrap.min.css" rel="stylesheet" />


<!-- Modal -->
<div class="modal fade" id="exampleModalLong" tabindex="-1" role="dialog" aria-labelledby="exampleModalLongTitle" aria-hidden="true">
  <div class="modal-dialog" role="document">
    <div class="modal-content">
      <div class="modal-header">
        <h5 class="modal-title" id="exampleModalLongTitle">Modal title</h5>
        <button type="button" class="close" data-dismiss="modal" aria-label="Close">
      <span aria-hidden="true">&times;</span>
    </button>
      </div>
      <div class="progress">
        <div id="progressbar" class="progress-bar" role="progressbar" aria-valuenow="0" aria-valuemin="0" aria-valuemax="100"></div>
      </div>
      <div class="modal-body">
        Cras mattis consectetur purus sit amet fermentum. Cras justo odio, dapibus ac facilisis in, egestas eget quam. Morbi leo risus, porta ac consectetur ac, vestibulum at eros. Praesent commodo cursus magna, vel scelerisque nisl consectetur et. Vivamus sagittis
        lacus vel augue laoreet rutrum faucibus dolor auctor. Aenean lacinia bibendum nulla sed consectetur. Praesent commodo cursus magna, vel scelerisque nisl consectetur et. Donec sed odio dui. Donec ullamcorper nulla non metus auctor fringilla. Cras
        mattis consectetur purus sit amet fermentum. Cras justo odio, dapibus ac facilisis in, egestas eget quam. Morbi leo risus, porta ac consectetur ac, vestibulum at eros. Praesent commodo cursus magna, vel scelerisque nisl consectetur et. Vivamus
        sagittis lacus vel augue laoreet rutrum faucibus dolor auctor. Aenean lacinia bibendum nulla sed consectetur. Praesent commodo cursus magna, vel scelerisque nisl consectetur et. Donec sed odio dui. Donec ullamcorper nulla non metus auctor fringilla.
        Cras mattis consectetur purus sit amet fermentum. Cras justo odio, dapibus ac facilisis in, egestas eget quam. Morbi leo risus, porta ac consectetur ac, vestibulum at eros. Praesent commodo cursus magna, vel scelerisque nisl consectetur et. Vivamus
        sagittis lacus vel augue laoreet rutrum faucibus dolor auctor. Aenean lacinia bibendum nulla sed consectetur. Praesent commodo cursus magna, vel scelerisque nisl consectetur et. Donec sed odio dui. Donec ullamcorper nulla non metus auctor fringilla.
        sagittis lacus vel augue laoreet rutrum faucibus dolor auctor. Aenean lacinia bibendum nulla sed consectetur. Praesent commodo cursus magna, vel scelerisque nisl consectetur et. Donec sed odio dui. Donec ullamcorper nulla non metus auctor fringilla.
        Cras mattis consectetur purus sit amet fermentum. Cras justo odio, dapibus ac facilisis in, egestas eget quam. Morbi leo risus, porta ac consectetur ac, vestibulum at eros. Praesent commodo cursus magna, vel scelerisque nisl consectetur et. Vivamus
        sagittis lacus vel augue laoreet rutrum faucibus dolor auctor. Aenean lacinia bibendum nulla sed consectetur. Praesent commodo cursus magna, vel scelerisque nisl consectetur et. Donec sed odio dui. Donec ullamcorper nulla non metus auctor fringilla.

      </div>
      <div class="modal-footer">
        <button type="button" class="btn btn-secondary" data-dismiss="modal">Close</button>
        <button type="button" class="btn btn-primary">Save changes</button>
      </div>
    </div>
  </div>
</div>