Bootstrap 4折叠手风琴-始终打开一个面板

Question

我在手风琴中使用Bootstrap 4.0的折叠组件，类似于他们在docs上的组件。

<div id="accordion">
  <div class="card">
    <div class="card-header" id="headingOne">
      <h5 class="mb-0">
        <button class="btn btn-link" data-toggle="collapse" data-target="#collapseOne" aria-expanded="true" aria-controls="collapseOne">
          Collapsible Group Item #1
        </button>
      </h5>
    </div>

    <div id="collapseOne" class="collapse show" aria-labelledby="headingOne" data-parent="#accordion">
      <div class="card-body">
        Anim pariatur cliche reprehenderit, enim eiusmod high life accusamus terry richardson ad squid. 3 wolf moon officia aute, non cupidatat skateboard dolor brunch. Food truck quinoa nesciunt laborum eiusmod. Brunch 3 wolf moon tempor, sunt aliqua put a bird on it squid single-origin coffee nulla assumenda shoreditch et. Nihil anim keffiyeh helvetica, craft beer labore wes anderson cred nesciunt sapiente ea proident. Ad vegan excepteur butcher vice lomo. Leggings occaecat craft beer farm-to-table, raw denim aesthetic synth nesciunt you probably haven't heard of them accusamus labore sustainable VHS.
      </div>
    </div>
  </div>
  <div class="card">
    <div class="card-header" id="headingTwo">
      <h5 class="mb-0">
        <button class="btn btn-link collapsed" data-toggle="collapse" data-target="#collapseTwo" aria-expanded="false" aria-controls="collapseTwo">
          Collapsible Group Item #2
        </button>
      </h5>
    </div>
    <div id="collapseTwo" class="collapse" aria-labelledby="headingTwo" data-parent="#accordion">
      <div class="card-body">
        Anim pariatur cliche reprehenderit, enim eiusmod high life accusamus terry richardson ad squid. 3 wolf moon officia aute, non cupidatat skateboard dolor brunch. Food truck quinoa nesciunt laborum eiusmod. Brunch 3 wolf moon tempor, sunt aliqua put a bird on it squid single-origin coffee nulla assumenda shoreditch et. Nihil anim keffiyeh helvetica, craft beer labore wes anderson cred nesciunt sapiente ea proident. Ad vegan excepteur butcher vice lomo. Leggings occaecat craft beer farm-to-table, raw denim aesthetic synth nesciunt you probably haven't heard of them accusamus labore sustainable VHS.
      </div>
    </div>
  </div>
  <div class="card">
    <div class="card-header" id="headingThree">
      <h5 class="mb-0">
        <button class="btn btn-link collapsed" data-toggle="collapse" data-target="#collapseThree" aria-expanded="false" aria-controls="collapseThree">
          Collapsible Group Item #3
        </button>
      </h5>
    </div>
    <div id="collapseThree" class="collapse" aria-labelledby="headingThree" data-parent="#accordion">
      <div class="card-body">
        Anim pariatur cliche reprehenderit, enim eiusmod high life accusamus terry richardson ad squid. 3 wolf moon officia aute, non cupidatat skateboard dolor brunch. Food truck quinoa nesciunt laborum eiusmod. Brunch 3 wolf moon tempor, sunt aliqua put a bird on it squid single-origin coffee nulla assumenda shoreditch et. Nihil anim keffiyeh helvetica, craft beer labore wes anderson cred nesciunt sapiente ea proident. Ad vegan excepteur butcher vice lomo. Leggings occaecat craft beer farm-to-table, raw denim aesthetic synth nesciunt you probably haven't heard of them accusamus labore sustainable VHS.
      </div>
    </div>
  </div>
</div>

因此，默认情况下将扩展项目＃1。然后，当您单击项目＃3时，＃1关闭并且＃3展开...完美！

但是，默认操作是，如果展开项目＃3并单击该标题，则面板将关闭，并且仅留下标题列表。我想更进一步，如果我们关闭项目＃3，项目＃1将会展开，因此如果没有其他选择，它将是打开的“默认”面板。

我已经看到了一个Bootstrap3 的解决方案，其中一个面板始终处于打开状态，但是我希望能够有一个特定的面板（项目1）作为作为备份打开的面板。这是易于参考的脚本：

$('.panel-heading a').on('click',function(e){
    if($(this).parents('.panel').children('.panel-collapse').hasClass('in')){
        e.stopPropagation();
    }
    // You can also add preventDefault to remove the anchor behavior that makes
    // the page jump
    // e.preventDefault();
});

Answer 1

您可以使用折叠隐藏事件。在这种情况下，请使用，因为 0 是第一个.eq(0)可折叠 div的索引。

$('.collapse').on('hidden.bs.collapse', function () {
    $('.collapse').eq(0).collapse('show');
})

更进一步，您可以default向父#accordion 添加一个新的数据变量...

<div id="accordion" class="accordion" data-default="1">..</div>

然后更改 jQuery 以使用该变量。

/* default accordion variable method */
$('.collapse').on('hidden.bs.collapse', function () {
  var defaultDiv = $($(this).data("parent")).data("default");
  $('.collapse').eq(defaultDiv-1).collapse('show');
})

演示： https: //www.codeply.com/go/NilPIQD9oi

另一种选择是防止任何打开的手风琴自行关闭，正如我在这个答案中解释的那样。