Add copy-to-clipboard button for room short id

src/app/components/creator/room-creator-page/room-creator-page.component.html

@@ -13,6 +13,9 @@
             <h3>
               {{ 'room-page.session-id' | translate}}: {{ room.shortId.slice(0, 4) }} {{  room.shortId.slice(4, 8) }}
             </h3>
+            <button mat-icon-button (click)="copyShortId()">
+              <mat-icon>cloud_download</mat-icon>
+            </button>
           </mat-card-subtitle>
         </mat-card-header>
         <span class="fill-remaining-space"></span>

src/app/components/creator/room-creator-page/room-creator-page.component.ts

@@ -119,5 +119,19 @@ export class RoomCreatorPageComponent extends RoomPageComponent implements OnIni
     });
     dialogRef.componentInstance.roomId = this.room.id;
   }
+
+  copyShortId(): void {
+    let selBox = document.createElement('textarea');
+    selBox.style.position = 'fixed';
+    selBox.style.left = '0';
+    selBox.style.top = '0';
+    selBox.style.opacity = '0';
+    selBox.value = this.room.shortId;
+    document.body.appendChild(selBox);
+    selBox.focus();
+    selBox.select();
+    document.execCommand('copy');
+    document.body.removeChild(selBox);
+  }
 }