Angular 2 CanActivate is called twice

Question

I am faced with a problem with route guards with Angular.

My CanActivate guard is called twice when navigating to a page that is not permitted because I\'m not logged in

Answer 1

I noticed it will not work with Hash: Below is my example, and notice: the code below will call penModalDialogInvalid() twice as I use

providers: [{provide:LocationStrategy,useClass:HashLocationStrategy}],



   @Injectable()
export class UserDetailsGuard implements CanActivate {


constructor(private _router:Router,
    private winRef: WindowRef){}

 canActivate(route:ActivatedRouteSnapshot,state: RouterStateSnapshot ) : boolean {

    let id=+route.url[0].path;

    if (isNaN(id) || id <1 ){
        this.winRef.nativeWindow.openModalDialogInvalid();
        //this._router.navigate(['/pagenotfound']);
        return false;
    }
    return true;

} 

}

If I comment out the navigation line above, it will call the function once!!!! otherwise twice except in Firefox and all Firefox-based browsers!!!! why???? I dunno!!!!!