如何默认选择第一项，然后在angular 6中突出显示所选的下一项json数据

selectedItem: any;
jsonData: any[] = [
  { id: 1, name: 'Item 1' },
  { id: 2, name: 'Item 2' },
  { id: 3, name: 'Item 3' }
];

<select [(ngModel)]="selectedItem">
  <option *ngFor="let item of jsonData" [value]="item">{{ item.name }}</option>
</select>

<select [(ngModel)]="selectedItem">
  <option *ngFor="let item of jsonData" [value]="item" [ngClass]="{'selected-item': item === selectedItem}" [selected]="item === selectedItem">{{ item.name }}</option>
</select>

.selected-item {
  background-color: yellow;
}