Sample of linking google analytics with angular

angular.ts

// Google Analytics Service

init() {
    if (!this.scriptsLoaded) {
      this.insertMainScript();
    }
  }

  trackPageViews() {
    return this.router.events.pipe(
      filter(() => this.scriptsLoaded),
      filter((event: RouterEvent) => event instanceof NavigationEnd),
      tap((event: NavigationEnd) => this.trackSinglePageView(event))
    );
  }

  setCurrentUser(userId: string) {
    // we set this in the get user function of Auth service
    // to avoid this being set several times we have a flag to check if it was set initially
    if (this.googleAnalyticsId && this.scriptsLoaded && !this.userIdSet) {
      gtag('set', { user_id: userId });
      this.userIdSet = true;
    }
  }

  private trackSinglePageView(event: NavigationEnd) {
    if (this.googleAnalyticsId && this.scriptsLoaded) {
      gtag('config', this.googleAnalyticsId, { page_path: event.urlAfterRedirects, send_page_view: true });
    }
  }

  private insertMainScript() {
    if (this.googleAnalyticsId) {
      const script: HTMLScriptElement = this.renderer2.createElement('script');
      script.type = 'text/javascript';
      script.onload = this.insertSecondHalfOfScript.bind(this);
      script.src = `https://googletagmanager.com/gtag/js?id=${this.googleAnalyticsId}`;
      script.text = '';
      this.renderer2.appendChild(this.document.body, script);
    }
  }

  private insertSecondHalfOfScript() {
    const script: HTMLScriptElement = this.renderer2.createElement('script');
    script.type = 'text/javascript';
    script.src = '/assets/config/google-analytics.js';
    script.text = '';
    this.renderer2.appendChild(this.document.body, script);
    script.onload = () => {
      this.scriptsLoaded = true;
    };
  }

// App component
ngOnInit() {
  this.googleAnalytics.init();
  this.googleAnalytics.trackPageViews().pipe(takeUntil(this.destroySubject$)).subscribe();
}