Show activity Indicator while loading a lazy loaded Module in Angular 2

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You can listen for two router events:

  • RouteConfigLoadStart
  • RouteConfigLoadEnd

They fire when a lazy loaded module is being loaded. The advantage of using these over the standard router events such as NavigationStart is that they won’t fire on every route change.

Listen to them in your root AppComponent to show / hide your spinner.

app.component.ts

import { Router, RouteConfigLoadStart, RouteConfigLoadEnd } from '@angular/router';

...

export class AppComponent implements OnInit {

    loadingRouteConfig: boolean;

    constructor (private router: Router) {}

    ngOnInit () {
        this.router.events.subscribe(event => {
            if (event instanceof RouteConfigLoadStart) {
                this.loadingRouteConfig = true;
            } else if (event instanceof RouteConfigLoadEnd) {
                this.loadingRouteConfig = false;
            }
        });
    }
}

app.component.html

Just a simple string here, but you could use a spinner component.

<router-outlet></router-outlet>

<ng-container *ngIf="loadingRouteConfig">Loading route config...</ng-container>

I’m using this approach with Angular v4.2.3

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