Javascript 在嵌套窗体上使用索引进行角度跟踪

如果我有一个使用*ngFor的三级嵌套表单，并且没有唯一的id或字段，那么我可以在每个trackBy函数中使用每个*ngFor的索引吗

<ng-container class="step-container" *ngFor="let step of trainingForm.controls['steps'].controls; let i = index;  trackBy: trackByIndex">

<ng-container [formGroupName]="j" *ngFor="let question of step.controls['questions'].controls; let j = index" trackBy: trackByIndex2">

<ng-container [formGroupName]="k" *ngFor="let option of question.controls['response'].controls; let k = index;"  class="col-md-12 col-sm-12" trackBy: trackByIndex3">

  trackByIndex1(index: number, data: any) { return index; }
  trackByIndex2(index: number, data: any) { return index; }
  trackByIndex3(index: number, data: any) { return index; }