Accordion doesn't work in Bootstrap 4 collapse

Question

https://fiddle.jshell.net/8v72rtxb/
I have the following code.

  <div class="menu-horizontal container">
    <div class="row menu-container" id="menu">
      <div class="col-md-3 menu-item">
        <a data-toggle="collapse" class="collapsed collapse-toggle" data-parent="#menu" href="#studies-collapse" aria-expanded="false" aria-controls="collapseExample">
          Studies
        </a>
        <div class="collapse" id="studies-collapse">
          <div class="container">
            <div class="row">
              Something...
            </div>
          </div>
        </div>
      </div>

      <div class="col-md-3 menu-item">
        <a data-toggle="collapse" class="collapsed collapse-toggle" data-parent="#menu" href="#research-collapse" aria-expanded="false" aria-controls="collapseExample">
          Research
        </a>
        <div class="collapse" id="research-collapse">
          <div class="container">
            <div class="row">
              Something...
            </div>
          </div>
        </div>
      </div>

    </div>
  </div>

I have no idea why data-parent doesn't work though. Expand one collapse div doesn't close the other collapse. I tried to copy the code from the example of bootstrap, but it still doesn't work. Also in my project, I include jquery.js before bootstrap.min.js . I have checked some other questions, they said that bootstrap.min.js might have been included twice. But should that be the case?
Thanks for reading!

Answer 1

I figured a workaround for this. Even without using the data-parent attribute. https://fiddle.jshell.net/zyd1vL4o/

$(document).ready(function(){
    $('.collapse').on('show.bs.collapse', function (e) {
        $('.collapse').collapse("hide")
    })
})

Answer 2

Once go through this jsfiddle

And here is html code,

<div id="accordion" role="tablist" aria-multiselectable="true">
  <div class="card">
    <div class="card-header" role="tab" id="headingOne">
      <h5 class="mb-0">
        <a data-toggle="collapse" data-parent="#accordion" href="#collapseOne" aria-expanded="true" aria-controls="collapseOne">
          Studies
        </a>
      </h5>
    </div>

    <div id="collapseOne" class="collapse " role="tabpanel" aria-labelledby="headingOne">
      <div class="card-block">
        <div id="studies-collapse">
          <div class="container">
            <div class="row">
              <div class="col-md-3">
                <a href="" class="menu-subitem">
                    Study Guides
                </a>
                <a href="" class="menu-subitem">
                    Counselling and Instructions
                </a>
                <a href="" class="menu-subitem">
                    Student Laboratory
                </a>
                <a href="" class="menu-subitem">
                    Student Exchange
                </a>
              </div>
              <div class="col-md-3">
                <a href="" class="menu-subitem">
                    Post‐graduate studies
                </a>
                <a href="" class="menu-subitem">
                    Theses
                </a>
                <a href="" class="menu-subitem">
                    Exams
                </a>
              </div>
            </div>
          </div>
        </div>
      </div>
    </div>
  </div>
  <div class="card">
    <div class="card-header" role="tab" id="headingTwo">
      <h5 class="mb-0">
        <a class="collapsed" data-toggle="collapse" data-parent="#accordion" href="#collapseTwo" aria-expanded="false" aria-controls="collapseTwo">
          Research
        </a>
      </h5>
    </div>
    <div id="collapseTwo" class="collapse" role="tabpanel" aria-labelledby="headingTwo">
      <div class="card-block">
        <div  id="research-collapse">
          <div class="container">
            <div class="row">
              <div class="col-md-3">
                <a href="" class="menu-subitem">
                    Study Guides
                </a>
                <a href="" class="menu-subitem">
                    Counselling and Instructions
                </a>
                <a href="" class="menu-subitem">
                    Student Laboratory
                </a>
                <a href="" class="menu-subitem">
                    Student Exchange
                </a>
              </div>
              <div class="col-md-3">
                <a href="" class="menu-subitem">
                    Post‐graduate studies
                </a>
                <a href="" class="menu-subitem">
                    Theses
                </a>
                <a href="" class="menu-subitem">
                    Exams
                </a>
              </div>
            </div>
          </div>
        </div>
      </div>
    </div>
  </div>
</div>

Answer 3

Use:

 <div class="menu-horizontal container"> <div class="row menu-container" id="menu"> <div class="col-md-3 menu-item"> <a data-toggle="collapse" class="collapsed" data-target="#studies-collapse" href="#studies-collapse" aria-expanded="false" aria-controls="studies-collapse"> Studies </a> <div class="collapse" id="studies-collapse" data-parent="#menu"> <div class="container"> <div class="row"> Something... </div> </div> </div> </div> <div class="col-md-3 menu-item"> <a data-toggle="collapse" class="collapsed" data-target="#research-collapse" href="#research-collapse" aria-expanded="false" aria-controls="research-collapse"> Research </a> <div class="collapse" id="research-collapse" data-parent="#menu"> <div class="container"> <div class="row"> Something... </div> </div> </div> </div> </div> </div> 

Answer 4

import 'bootstrap/js/dist/collapse';

Include this in your file and the collapse should work.

Answer 5

If its not closing, then you might not be properly linking to to your bootstrap js. You shouldn't need to add anything extra. check for the following js files:

• bootstrap.min.js
• bootstrap.bundle.min.js

If you're creating a bootstrap theme then in the functions do this:
wp_register_script( 'write your theme name here', get_template_directory_uri() . '/bootstrap/js/bootstrap.min.js', array( 'jquery' ) );