如何全选?

就“多选”而言:

https://material.angular.io/components/select/overview

HTML

<mat-form-field>
  <mat-select placeholder="Toppings" [formControl]="toppings" multiple>
    <mat-option *ngFor="let topping of toppingList" [value]="topping">{{topping}}</mat-option>
  </mat-select>
</mat-form-field>

TS 从“@角度/核心”导入{组件}; 从“@角度/形状”导入{FormControl};

/** @title Select with multiple selection */
@Component({
  selector: 'select-multiple-example',
  templateUrl: 'select-multiple-example.html',
  styleUrls: ['select-multiple-example.css'],
})
export class SelectMultipleExample {
  toppings = new FormControl();

  toppingList = ['Extra cheese', 'Mushroom', 'Onion', 'Pepperoni', 'Sausage', 'Tomato'];
}

有没有办法“预先检查”像“额外奶酪”、“意大利香肠”这样的盒子?