demo/src/app/components/+dropdown/demos/trigger-by-isopen-property/trigger-by-isopen-property.html
<div class="btn-group" dropdown #dropdown="bs-dropdown" [autoClose]="false">
<button dropdownToggle type="button" class="btn btn-primary dropdown-toggle">
Button dropdown <span class="caret"></span>
</button>
<ul *dropdownMenu class="dropdown-menu" role="menu">
<li role="menuitem"><a class="dropdown-item" href="#">Action</a></li>
<li role="menuitem"><a class="dropdown-item" href="#">Another action</a>
</li>
<li role="menuitem"><a class="dropdown-item" href="#">Something else
here</a></li>
</ul>
</div>
<button type="button" class="btn btn-primary" (click)="dropdown.isOpen = !dropdown.isOpen">Toggle</button>