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Bootstrap class: .dropright

<div class="btn-group dropright">
  <button type="button" class="btn btn-secondary dropdown-toggle" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">
    Dropright
  </button>
  <div class="dropdown-menu" x-placement="right-start" style="position: absolute; transform: translate3d(111px, 0px, 0px); top: 0px; left: 0px; will-change: transform;">
    <a class="dropdown-item" href="#">Action</a>
    <a class="dropdown-item" href="#">Another action</a>
  </div>
</div>

Preview

Sass source

/* _button-group.scss:81 */
.dropright &::after {
  margin-left: 0;
}

/* _dropdown.scss:56 */
.dropright {
  .dropdown-menu {
    top: 0;
    right: auto;
    left: 100%;
    margin-top: 0;
    margin-left: $dropdown-spacer;
  }

  .dropdown-toggle {
    @include caret(right);
    &::after {
      vertical-align: 0;
    }
  }
}

Uses variables

/* _button-group.scss:81 */


/* _dropdown.scss:56 */
$dropdown-spacer