如何循环Angular FormArray -当前设置为循环中的最后一项

import { Component, OnInit } from '@angular/core';
import { FormBuilder, FormGroup, FormArray } from '@angular/forms';

@Component({
  selector: 'app-example',
  templateUrl: './example.component.html',
  styleUrls: ['./example.component.css']
})
export class ExampleComponent implements OnInit {
  form: FormGroup;

  constructor(private fb: FormBuilder) { }

  ngOnInit() {
    this.form = this.fb.group({
      items: this.fb.array([])
    });
  }

  get items() {
    return this.form.get('items') as FormArray;
  }
}

<form [formGroup]="form">
  <div formArrayName="items">
    <div *ngFor="let item of items.controls; let last = last" [formGroupName]="last ? items.length - 1 : item">
      <!-- 表单控件的HTML代码 -->
      <input formControlName="name" placeholder="Name">
      <input formControlName="age" placeholder="Age">
    </div>
  </div>
</form>