误差与角度2形式所需的区别

Question

我正在使用角度2模板驱动形式工作。我有一个问题。value.errors.required和value.errors有什么区别。任何人都可以清楚地解释吗？如果我使用必填项，则会收到类似“ ERROR 错误：无法读取null属性“ required”。正确的是“ zipcode.errors.required”（或zipcode.errors）

演示：https://stackblitz.com/edit/angular-6-template-driven-form-validation-kdkans?file=app/app.component.html

<div *ngIf="zipcode1.invalid || zipcode2.invalid)&&forms.submitted&& 
(zipcode1.errors.required || zipcode2.errors.required")>

<div *ngIf="zipcode1.errors.required || zipcode2.errors.required">Please 
type</div>

</div>

 <div *ngIf="zipcode1.invalid || zipcode2.invalid)&&forms.submitted&& 
(zipcode1.errors.required || zipcode2.errors.required ")>

<div *ngIf="zipcode1.errors.required || zipcode2.errors.required">Please 
type</div>

</div>

和

<div *ngIf="zipcode1.errors|| zipcode2.errors">Please type</div>

</div>

<div *ngIf="zipcode1.invalid || zipcode2.invalid)&&forms.submitted&& 
(zipcode1.errors|| zipcode2.errors")>

<div *ngIf="zipcode1.errors|| zipcode2.errors">Please type</div>

 </div>