是否可以在Angular中添加跨字段异步验证？

import { FormGroup, FormControl } from '@angular/forms';
import { Observable } from 'rxjs';
import { map } from 'rxjs/operators';

// 自定义验证器函数
const passwordMatchValidator = (control: FormGroup): Observable<any> => {
  const password = control.get('password').value;
  const confirmPassword = control.get('confirmPassword').value;

  // 进行异步验证
  return fakeAsyncValidation(password, confirmPassword).pipe(
    map(isMatch => {
      // 如果密码与确认密码不匹配，则返回验证错误
      return isMatch ? null : { passwordMismatch: true };
    })
  );
};

// 模拟异步验证
const fakeAsyncValidation = (password: string, confirmPassword: string): Observable<boolean> => {
  // 这里可以使用异步请求或其他方式进行验证
  return new Observable<boolean>(observer => {
    // 模拟异步验证延迟
    setTimeout(() => {
      // 检查密码与确认密码是否匹配
      const isMatch = password === confirmPassword;
      observer.next(isMatch);
      observer.complete();
    }, 2000); // 模拟2秒延迟
  });
};

// 创建表单
const form = new FormGroup({
  password: new FormControl(''),
  confirmPassword: new FormControl('')
}, { validators: passwordMatchValidator });

// 在模板中使用表单
<form [formGroup]="form">
  <input type="password" formControlName="password" placeholder="Password">
  <input type="password" formControlName="confirmPassword" placeholder="Confirm Password">
  <div *ngIf="form.hasError('passwordMismatch')">Passwords do not match</div>
</form>