Tracking Google Analytics Page Views in Angular2

Question

I managed to get this working by subscribing to changes on the router, checking that the route had actually changed (I was getting multiple events on some routes at times) and then sending the new path to Google.

app.component.ts

import { ... } from '...';

// Declare ga function as ambient
declare var ga:Function;

@Component({ ... })

export class AppComponent {
    private currentRoute:string;

    constructor(_router:Router) {
        // Using Rx's built in `distinctUntilChanged ` feature to handle url change c/o @dloomb's answer
        router.events.pipe(distinctUntilChanged((previous: any, current: any) => {
            // Subscribe to any `NavigationEnd` events where the url has changed
            if(current instanceof NavigationEnd) {
                return previous.url === current.url;
            }
            return true;
        })).subscribe((x: any) => {
            ga('set', 'page', x.url);
            ga('send', 'pageview')
        });
      }
    }
}

You also need to include the google analytics code in your main index file before loading your angular2 app so that the global ga object exists, but you don’t want to send the initial view twice. In order to do this, remove the following line from the GA script

index.html

<script>
  (function(i,s,o,g,r,a,m){...})(window,document,'script','https://www.google-analytics.com/analytics.js','ga');

  ga('create', 'UA-XXXXXXXX-X', 'auto');
  // Remove this line to avoid sending the first page view twice.
  //ga('send', 'pageview');

</script>
<!-- 
    Load your ng2 app after ga. 
    This style of deferred script loading doesn't guarantee this will happen
    but you can use Promise's or what works for your particular project. 
-->
<script defer type="text/javascript" src="/app.js"></script>

Using a third party library

As an alternative to implementing GA yourself, the library Angulartics2 is also a popular tool for implementing GA tracking and also integrates with other analytics vendors as well.

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