title: how to check a div is hidden or visible in angular 4?
body: <p>i have declared "sample" variable as false in a component and assigned *ngIf Condition check in HTML.</p>
  
  <p>obviously it hides the div</p>
  
  <p>but here i want to know check whether that div is hidden or visible?</p>
  
  <p>Thanks in Advance</p>
  
  <p><a href="https://i.stack.imgur.com/fBB1B.png" rel="nofollow noreferrer">Image</a></p>