Angular.io hide
<div [style.visibility]="(numberOfUnreadAlerts == 0) ? 'hidden' : 'visible' ">
COUNTER: {{numberOfUnreadAlerts}}
</div>
GutoTrosla
<div [style.visibility]="(numberOfUnreadAlerts == 0) ? 'hidden' : 'visible' ">
COUNTER: {{numberOfUnreadAlerts}}
</div>