Angular 2表:如何使用键盘箭头切换大小写

import { Component, HostListener } from '@angular/core';

@Component({
  selector: 'app-my-component',
  template: `
    <input [(ngModel)]="text" (keydown)="onKeyDown($event)">
  `
})
export class MyComponent {
  text: string = '';

  @HostListener('window:keydown', ['$event'])
  onKeyDown(event: KeyboardEvent) {
    // 在这里处理键盘事件
  }
}

onKeyDown(event: KeyboardEvent) {
  if (event.key === 'ArrowUp') {
    this.text = this.text.toUpperCase();
  } else if (event.key === 'ArrowDown') {
    this.text = this.text.toLowerCase();
  }
}

<input [(ngModel)]="text" (keydown)="onKeyDown($event)">