Reactive Forms:如何在Angular 7/8/9中的稍后时间点将新的FormGroup或FormArray添加到现有的FormGroup中

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

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

  constructor(private fb: FormBuilder) {
    this.form = this.fb.group({
      existingGroup: this.fb.group({
        control1: [''],
        control2: ['']
      }),
      formArray: this.fb.array([])
    });
  }

  ngOnInit(): void {
    // 模拟在稍后的时间点添加新的 FormGroup
    setTimeout(() => {
      const newFormGroup = this.fb.group({
        newControl1: [''],
        newControl2: ['']
      });
      this.form.addControl('newGroup', newFormGroup);
    }, 2000);

    // 模拟在稍后的时间点添加新的 FormArray
    setTimeout(() => {
      const newFormArray = this.fb.array([
        this.fb.control(''),
        this.fb.control('')
      ]);
      this.form.setControl('newFormArray', newFormArray);
    }, 4000);
  }
}