为什么格式＆＃39; HH：mm＆＃39;不在此DatePipe中工作？

Question

我正在尝试在Date字段中显示input对象并仅显示分钟

<mat-form-field>
  <input matInput type="time" placeholder="Choose a time" 
       [(ngModel)]="appointmentTime"
       [ngModel]="appointmentTime  | date:'HH:mm'"/>
</mat-form-field>

但是，时间没有正确显示 - 实际上根本没有显示：

在课堂上，appointmentTime和appointmentDate被初始化为

public appointmentDate = new Date();
public appointmentTime = new Date();

Answer 1

 <input matInput type="time" placeholder="Choose a time" 
       [ngModel]="appointmentTime  | date:'HH:mm'"/>