如何导航/聚焦到Angular2中的下一个项目? [英] How to navigate/focus to the next item in Angular2?

问题描述

我想使用箭头键专注于下一个项目.
在keydown事件处理程序中，我使用event.currentTarget.nextSibling访问下一项.
还有另一种方法可以实现这一目标吗?
在事件处理程序中，我想使用JQuery来做到这一点.这该怎么做?

I want to focus to the next item using Arrow keys.
In keydown event handler, I use event.currentTarget.nextSibling to access the next item.
Is there another way to accomplish this?
In the event handler, I want to use JQuery to do this. How to do this?

<ul>
    <li *ngFor = "let work of works" tabindex="-1" 
        (keydown.ArrowDown)="handleKeyEvent( $event, 'Arrow Down' )">
        <div class="guide-label">
            <div>{{work.cd}}</div>
            <div>{{work.name}}</div>
        </div>
    </li>
</ul>

export class WorkComponent {
    ...
    handleKeyEvent(event: Event): void {

        event.currentTarget.nextSibling.focus();
        event.preventDefault();
    }
}

推荐答案

创建一个焦点指令(并将其注册到您的NgModule中)，当输入值更改为true时，该指令在主机元素上调用focus():

Create a focus directive (and register it in your NgModule) that calls focus() on the host element when the input value changes to true:

@Directive({
  selector : '[myFocus]'
})
class MyFocus {
  constructor(public renderer: Renderer, public elementRef: ElementRef) {}

  @Input()
  set myFocus(value :boolean) {
    if(value) {
      this.renderer.invokeElementMethod(
          this.elementRef.nativeElement, 'focus', []);
    }
  }
}

添加选择器和一个绑定，该绑定在应被聚焦时将true或false传递给指令:

Add the selector and a binding that passes true or false to the directive when it is supposed to be focused:

<li *ngFor = "let work of works let idx=index" tabindex="-1" 
    [myFocus]="idx == focusedIdx" (keydown.ArrowDown)="handleKeyEvent( $event, 'Arrow Down' )">

在关键事件上更新focusedIdx:

       handleKeyEvent(event: Event): void {
            this.focusedIdx++;
        }

另请参见角度2:关注新添加的输入元素

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