EVERYTHING YOU NEED TO KNOW ON SECURING YOUR ANGULAR 2+ SPA --> User service

auth.service.ts

import {Injectable} from '@angular/core';
import {UserService} from "./user.service";
import {ApiHandler} from "./api-handler.service";
import {JwtHelper} from "../helpers/jwt-helper";
import {Observable} from "rxjs";
import {RequestMethod} from "@angular/http";

import 'rxjs/add/operator/do';
import 'rxjs/add/operator/map';

@Injectable()
export class AuthService {
  private _jwt: JwtHelper = new JwtHelper();
  private redirectUrl: string;
  public message: string;

  constructor(private _apiHandler: ApiHandler, private _userService: UserService) {
  }


  /**
   * check for expiration and if token is still existing or not
   * @return {boolean}
   */
  isAuthenticated(): boolean {
    return localStorage.getItem('token') != null && !this._jwt.isTokenExpired();
  }

  setRedirectUrl(url: string): void {
    this.redirectUrl = url;
  }

  getRedirectUrl(): string {
    return this.redirectUrl;
  }

  /**
   * this is used to clear anything that needs to be removed
   */
  clear(): void {
    localStorage.clear();
  }

  /**
   * this returns the token for the user
   * @param email
   * @param password
   */
  authenticate(email: string, password: string): Observable<string> {
    return this._apiHandler.callService("/user/login", RequestMethod.Post, {email: email, password: password})
      .map(res => <string>res.text())
      .do((token: string) => {
        localStorage.setItem('token', token);
        this._userService.set(this._jwt.decodeToken());
      });
  }

  /**
   * this is used to alert our caller if we should go get token for next request or
   * to be carried out request
   *
   * @param threshold_seconds  is like a threshold to check if we should or not check for token
   * default we use 2min before the token expires
   *
   * @return {boolean}
   */
  shouldIGetToken(threshold_seconds: number = 120): boolean {
    let expDate = this._jwt.getTokenExpirationDate().valueOf() - (threshold_seconds * 1000);

    return new Date().valueOf() > expDate;
  }

  /**
   * this is used to retrieve a newer token since the current one is going to expire soon
   *
   */
  retrieveToken(): Observable<string> {
    return this._apiHandler.callService("/user/token", RequestMethod.Get)
      .map(res => <string>res.text())
      .do((token: string) => {
        this.clear();
        localStorage.setItem('token', token);
        this._userService.set(this._jwt.decodeToken());
      });
  }

}