加载外部脚本后无法访问组件

Question

我正在尝试在angular6应用程序中加载Google API。在触发load事件后，我真的无法更改组件中的任何内容。

看看脚本最后三行的注释

@Component({
  selector: 'my-app',
  template: '{{loaded}}',
})
export class AppComponent  {
  loaded = false;   
  constructor(){
    let node = document.createElement('script');
    node.src = 'https://apis.google.com/js/client.js?onload=__onGoogleLoaded';
    node.type = 'text/javascript';
    document.getElementsByTagName('head')[0].appendChild(node);

    window['__onGoogleLoaded'] = (ev) =>{
      console.log('here!!!!');// <----------------------------WORKING
      this.loaded = true;// <---------------------------------NOT WORKING
    }
    //this.loaded = true; <<----------------------------------WORKING
  }
}

https://stackblitz.com/edit/angular-qvwm3z?file=src%2Fapp%2Fapp.component.ts