打字稿：创建方法时对象可能为空

Question

I am getting an "Object is possibly null" error when creating the changePageSize method inside book-store.component.html. Apparently I have to initialize the object in the class, but I'm not sure how to do that, can anyone help me out. I am new to Typescript and Angular.

Answer 1

$event.target has type EventTarget . It has no value field. That's the reason of your issue.

To fix this issue you need to cast $event.target to correct type.

// template
<select ... (change)="changePageSize($event)">...</select>

// component
changePageSize(event: Event): void {
    const element = event.target as HTMLInputElement;
    const value = element.value;
}