demo/src/app/components/+collapse/demos/events/events.html
<div class="row">
<div class="col-md-3">
<button type="button" class="btn btn-primary" (click)="isCollapsed = !isCollapsed"
[attr.aria-expanded]="!isCollapsed" aria-controls="collapseEvent">Toggle collapse
</button>
</div>
<div class="col-md-9">
<pre class="card card-block card-header">Event: {{message}}</pre>
</div>
</div>
<hr>
<div id="collapseEvent" class="card card-block card-header"
(collapsed)="collapsed()" (expanded)="expanded()" [collapse]="isCollapsed">
<div class="well well-lg">Some content</div>
</div>