JAVASCRIPT

open bootstrap modal with javascript

$("#myModal").modal()

open modal event bootstrap

//This event fires immediately when the show instance method is called. 
$('#myModal').on('show.bs.modal', function (e) {
  // do something...
});

//This event is fired when the modal has been made visible to the user
$('#myModal').on('shown.bs.modal', function (e) {
  // do something...
});

//This event is fired immediately when the hide instance method has been called.
$('#myModal').on('hide.bs.modal', function (e) {
  // do something...
});

//This event is fired when the modal has finished being hidden
$('#myModal').on('hidden.bs.modal', function (e) {
  // do something...
})

bootstrap 4 start modal in modal

var modal_lv = 0;
$('.modal').on('shown.bs.modal', function (e) {
    $('.modal-backdrop:last').css('zIndex',1051+modal_lv);
    $(e.currentTarget).css('zIndex',1052+modal_lv);
    modal_lv++
});

$('.modal').on('hidden.bs.modal', function (e) {
    modal_lv--
});

open bootstrap modal using vanilla js

let el = document.getElementById("modal1");
new Modal(el).show();

bootstrap modal js

<div class="modal-body">
  <div class="container-fluid">
    <div class="row">
      <div class="col-md-4">.col-md-4</div>
      <div class="col-md-4 ml-auto">.col-md-4 .ml-auto</div>
    </div>
    <div class="row">
      <div class="col-md-3 ml-auto">.col-md-3 .ml-auto</div>
      <div class="col-md-2 ml-auto">.col-md-2 .ml-auto</div>
    </div>
    <div class="row">
      <div class="col-md-6 ml-auto">.col-md-6 .ml-auto</div>
    </div>
    <div class="row">
      <div class="col-sm-9">
        Level 1: .col-sm-9
        <div class="row">
          <div class="col-8 col-sm-6">
            Level 2: .col-8 .col-sm-6
          </div>
          <div class="col-4 col-sm-6">
            Level 2: .col-4 .col-sm-6
          </div>
        </div>
      </div>
    </div>
  </div>
</div>