在Angular渲染之前获取数据（Angular 2 +）

Question

在渲染html之前，我需要执行此代码。有任何想法吗？我查看了Promises，Callbacks和Observables

  voices;

  ngOnInit() {
    if ('speechSynthesis' in window) {
      speechSynthesis.onvoiceschanged = () => {
        this.voices = window.speechSynthesis.getVoices();
      };
    }
  }