How to print variable only once in ngFor?-CodePudding

and i need to print some "printDay" by condition only once, how can i do it?

  <div  *ngFor="let message of messages">
  <div  *ngIf="lastMessageDate !== firstMessageDate "  >{{printDay}}</div>
  <div [ngClass]="{'message__sent': message.messageType === 'sent'}" >
    <div >
      <span >{{message.name}} {{message.DATE | date: 'HH:mm'}}</span>
      <div >{{message.message}}</div>
      <div  *ngIf="message.send_diagnostic_data">
        <app-download-file (fileDownloadEvent)="downloadFile('log', message.UUID)"
                           [fileLabel]="'Отчет по логам'"></app-download-file>
        <app-download-file (fileDownloadEvent)="downloadFile('telemetry', message.UUID)"
                           [fileLabel]="'Отчет по телеметрии'"></app-download-file>
      </div>
    </div>
  </div>
</div>

CodePudding user response：

If you want to print something only in the first child you can use first directive:

<div *ngFor="let message of messages; first as isFirst">
    <div *ngIf="isFirst"> {{ printSomething() }} </div>
</div>