title: wrapping a click event into a *ngIf in Angular 2
body: <p>What is the best way to only use (click) when the screen size is less than 768 px in width using Angular 2. I have 
      (click)="isClassVisible = !isClassVisible;"
   but want to put it in something like 
      *ngIf="screenWidth &lt; 769 {(click)="isClassVisible = !isClassVisible;"}". 
  Not sure how to accomplish this in Angular 2. I know that isn't valid. Basically a nav item that has a secondary drop down should expand on hover on a desktop, and contract when mouse leaves. On mobile I want them to click the nav Item to open, but also close it if they click again. I can do it, but I can't figure out how to only make the click event visible in responsive mode.</p>