Angular 7 Authentication Guard Service

auth.guard.ts

import { Injectable } from '@angular/core';
import { ActivatedRouteSnapshot, CanActivate, CanLoad, Route, Router, RouterStateSnapshot } from '@angular/router';
import { Observable } from 'rxjs';
import { AuthenticationService } from 'src/app/Services/Authentication/authentication.service';


@Injectable({
  providedIn: 'root'
})
export class AuthGuard implements CanActivate, CanLoad {

  constructor(private authService: AuthenticationService, private router: Router) { }

  canActivate(route: ActivatedRouteSnapshot, state: RouterStateSnapshot): 
        Observable<boolean> | Promise<boolean> | boolean {
    if(! state || ! state.url) return false;

    let isValid: boolean = this.checkLoggedIn(state.url);
    if (isValid) {
      if (route.data && route.data.expectedClaim) {
        let expectedClaim = route.data.expectedClaim;
        isValid = this.checkClaim(expectedClaim);
      }
    }
    return isValid;
  }

  canLoad(route: Route): Observable<boolean> | Promise<boolean> | boolean {
    if(! route || ! route.path) return false;
    let isValid: boolean = this.checkLoggedIn(route.path);
    if (isValid) {
      if (route.data && route.data.expectedClaim) {
        let expectedClaim = route.data.expectedClaim;
        isValid = this.checkClaim(expectedClaim);
      }
    }
    return isValid;
  }

  checkLoggedIn(url: string): boolean {
    if(this.authService.checkLoggedIn()) {
      return true;
    }
    this.authService.redirectUrl = url;
    this.router.navigate(['/authentication/login']);
    return false;
  }

  checkClaim(claim: string) {
    let hasClaim: boolean = false;
    if (this.authService.currentUser) {
      hasClaim = this.authService.currentUser.claims.indexOf(claim) > -1;
    }
    return hasClaim;
  }

}