title: How to use @output to fire a boolean from child to parent
body: <p>Hi angular community,</p>
  
  <p>I want to fire an Event using @Output to hide or open/close a div containing others components. It's quite simple but I never use EventEmitter before, so i would like when hideDem is called it hide or open/close the div depending on other propreties comming from the child.ts</p>
  
  <p>child.html:</p>
  
  <pre><code> &lt;img type="button" label="Click" (click)="hideDem()" id="foldup" src="./assets/img/fold_up_blacksmall.png"/&gt;
  </code></pre>
  
  <p>child.comp.ts:</p>
  
  <pre><code>@Output() open: EventEmitter&lt;any&gt; = new EventEmitter();
  @Output() close: EventEmitter&lt;any&gt; = new EventEmitter();
  
  public hideDem(): void {
    this.hideMePartially = !this.hideMePartially;
    if (this.hideMePartially) {
      this.open.emit(true);
    } else {
      this.close.emit(false);
    }
  }
  </code></pre>
  
  <p>parent.comp.html</p>
  
  <pre><code> &lt;div class="daydetail"&gt; 
  &lt;div&gt;&lt;my-daydetail [showMePartially]="showVar" &gt;&lt;/my-daydetail&gt;&lt;/div&gt;
    &lt;div [hidden]="(close)=hideDem($event)"&gt;
      &lt;div&gt;
         &lt;app-pie-chart [minifiedMe]="hideMeup" &gt;&lt;/app-pie-chart&gt;
       &lt;/div&gt;
       &lt;div&gt;
         &lt;app-fonctionnaly [minifiedMe]="hideMeup"&gt;&lt;/app-fonctionnaly&gt;
       &lt;/div&gt;
       &lt;div&gt;
         &lt;app-my-verticalchart [minifiedMe]="hideMeup" &gt;&lt;/app-my-verticalchart&gt;
       &lt;/div&gt;
       &lt;div&gt;
         &lt;app-dysfonction [showMePartially]="hideVar"&gt;&lt;/app-dysfonction&gt;
       &lt;/div&gt;
     &lt;/div&gt; &lt;!-- End of hidden--&gt;
  &lt;/div&gt; &lt;!-- End of daydetail--&gt;
  </code></pre>