add google analytics

src/app/app.component.ts

@@ -1,4 +1,7 @@
 import { Component } from '@angular/core';
+import { NavigationEnd, Router } from '@angular/router';
+
+declare let gtag: Function;
 @Component({
   selector: 'app-root',
   templateUrl: './app.component.html',
@@ -6,5 +9,13 @@ import { Component } from '@angular/core';
 })
 export class AppComponent {
 
-  constructor() { }
+  constructor(public router: Router) {
+    this.router.events.subscribe(event => {
+      if (event instanceof NavigationEnd) {
+        gtag('config', 'G-48B6CKS0V6',{
+            'page_path': event.urlAfterRedirects
+          });
+      }
+    })
+  }
 }