Adds Google Analytics to every page as part of an SPFx Application Customizer.

COBSPFxApplicationCustomizer_GoogleAnalytics.ts

export default class CobSpFxGaApplicationCustomizer
  extends BaseApplicationCustomizer<ICobSpFxGaApplicationCustomizerProperties> {

  @override
  public onInit(): Promise<void> {
    /* update with YOUR Google Analytics tracking code: */
    let trackingCode: string = "UA-104299656-1";

    let scriptTagGA: HTMLScriptElement = document.createElement("script");
    scriptTagGA.text = `
        (function(i,s,o,g,r,a,m){i['GoogleAnalyticsObject']=r;i[r]=i[r]||function(){
        (i[r].q=i[r].q||[]).push(arguments)},i[r].l=1*new Date();a=s.createElement(o),
        m=s.getElementsByTagName(o)[0];a.async=1;a.src=g;m.parentNode.insertBefore(a,m)
        })(window,document,'script','https://www.google-analytics.com/analytics.js','ga');

        ga('create', '${trackingCode}', 'auto');
        ga('send', 'pageview');

      `;
    scriptTagGA.type = "text/javascript";
    document.getElementsByTagName("head")[0].appendChild(scriptTagGA);

    console.log(`OnInit: Added GA tracking script.`);
    return Promise.resolve<void>();
  }
}