join-room.component.html

<form (ngSubmit)="joinRoom(roomId.value)">
  <div fxLayout="row" fxLayoutAlign="center" fxLayoutGap="10px">
    <mat-form-field class="input-block">
      <input matInput #roomId placeholder="Room-Id" (keypress)="reset()"/>
    </mat-form-field>
    <button mat-fab color="primary" (click)="joinRoom(roomId.value)">
      <mat-icon>send</mat-icon>
    </button>
  </div>
  <mat-error *ngIf="!isExisting" class="errorForm">No room was found with this id.</mat-error>
  <mat-error *ngIf="noInput" class="errorForm">Please enter a room-id.</mat-error>
</form>