Check out example codes for "modal dismiss". It will help you in understanding the concepts better.

Code Example 1

<button type="button" class="btn btn-primary" data-toggle="modal" data-target="#modalId">
  ---
</button>

<div class="modal fade" id="modalId">
  <div class="modal-dialog" role="document">
    <div class="modal-content">
      <div class="modal-header">
        <h5 class="modal-title">title</h5>
		<button type="button" class="close" data-dismiss="modal" aria-label="Close">
        	<span aria-hidden="true">&times;</span>
        </button>
      </div>
      <div class="modal-body">
        
      </div>
      <div class="modal-footer">
  		<button type="button" class="btn btn-secondary" data-dismiss="modal">Close</button>
        <button type="submit" class="btn btn-primary">Save changes</button>
      </div>
    </div>
  </div>
</div>

Code Example 2

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

<!-- Modal -->
<div class="modal fade" id="exampleModalCenter" tabindex="-1" role="dialog" aria-labelledby="exampleModalCenterTitle" aria-hidden="true">
  <div class="modal-dialog modal-dialog-centered" 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">×</span>
        </button>
      </div>
      <div class="modal-body">
        ...
      </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>

Code Example 3

$('#myModal').modal('show')

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