typescript - Ionic2/Angular2/ typescript : How to access a DOM element in a function 2016

Question

我似乎找不到以最新方式访问 DOM 元素的“正确”方法:
Angular2 + Ionic2 + TypeScript。

所以考虑到下面这个场景......

问)如何在 sign() 函数中访问 sketchElement？

Settings.ts 模板:

<button full class="top-button-margin" (click)="sign()">
  Sign
  <ion-icon name="create"></ion-icon>
</button>
<img id="sketchElement" src="img/logo.png" padding *ngIf="showSignatureView">

我的 settings.ts 类:

@Page({
  templateUrl: 'build/pages/settings/settings.html'
})
export class SettingsPage {

  private currentUser: User = <User>{};
  private loggingOut: boolean = false;
  private currentConnection: string = "";
  private showSignatureView: boolean = false;

  constructor(
    private _platform: Platform,
    private _nav: NavController,
    private _events: Events,
    private _LoginService: LoginService,
    private _SessionService: SessionService,
    private _UIService: UIService) {

  }

  sign() {
    // I want to access sketchElement and its properties here.      
  }
}

Answer 1

您可以使用 ViewChild 装饰器。首先添加:

<img id="sketchElement"
     #sketchElement
     src="img/logo.png" padding *ngIf="showSignatureView">

并在您的组件中，添加相应的属性:

@Page({
  templateUrl: 'build/pages/settings/settings.html'
})
export class SettingsPage {
  @ViewChild('sketchElement')
  sketchElement:ElementRef;

  ngAfterViewInit() {
    // sketchElement is usable
  }
}

查看此插件:http://plnkr.co/edit/0TV3ppA0Gpwr5CjOWlAu?p=preview .

这个问题也可以帮助你:

• Calling a function in a child Angular2 Component?