May 23 2018

Angular 6 - JWT Authentication Example & Tutorial

Tutorial built with Angular 6.0.6 and Webpack 4.8

The following is a custom example and tutorial on how to setup a simple login page using Angular 6 and JWT authentication. For the same login tutorial in Angular 2/5 check out Angular 2/5 JWT Authentication Example & Tutorial.

Webpack 4.8 is used to compile and bundle all the project files, styling of the example is done with Bootstrap 4.

The tutorial code is available on GitHub at https://github.com/cornflourblue/angular-6-jwt-authentication-example

Here it is in action: (See on StackBlitz at https://stackblitz.com/edit/angular-6-jwt-authentication-example)

Update History:

  • 22 Jun 2018 - Made providers tree shakeable by adding providedIn: 'root' to the @Injectable decorator and removing provider references from @NgModule. Updated to Angular 6.0.6 and added auto-logout on "401 Unauthorized" response from the server api
  • 23 May 2018 - Built with Angular 6.0.2


Running the Angular 6 JWT Login Tutorial Example Locally

The tutorial example uses Webpack 4.8 to transpile the TypeScript code and bundle the Angular 6 modules together, and the webpack dev server is used as the local web server, to learn more about using webpack with TypeScript you can check out the webpack docs.

  1. Install NodeJS and NPM from https://nodejs.org/en/download/.
  2. Download or clone the tutorial project source code from https://github.com/cornflourblue/angular-6-jwt-authentication-example
  3. Install all required npm packages by running npm install from the command line in the project root folder (where the package.json is located).
  4. Start the application by running npm start from the command line in the project root folder.


Angular 6 Tutorial Project Structure

The project and code structure of the tutorial mostly follows the best practice recommendations in the official Angular Style Guide, with a few of my own tweaks here and there.

Each feature has it's own folder (home & login), other code such as services, models, guards etc are placed in folders prefixed with an underscore to easily differentiate them and group them together at the top of the folder structure.

The index.ts files in each folder are barrel files that group the exported modules from a folder together so they can be imported using the folder path instead of the full module path and to enable importing multiple modules in a single import (e.g. import { AuthenticationService, UserService } from '../_services').

Here's the tutorial project structure:


Below are brief descriptions and the code for the main files of the example authentication application, all the tutorial code is available in the github project linked at the top of the post.

 

Angular 6 Auth Guard

Path: /src/app/_guards/auth.guard.ts

The auth guard is used to prevent unauthenticated users from accessing restricted routes, it's used in app.routing.ts to protect the home page route. For more information about angular guards you can check out this post on the thoughtram blog.

import { Injectable } from '@angular/core';
import { Router, CanActivate, ActivatedRouteSnapshot, RouterStateSnapshot } from '@angular/router';

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

    constructor(private router: Router) { }

    canActivate(route: ActivatedRouteSnapshot, state: RouterStateSnapshot) {
        if (localStorage.getItem('currentUser')) {
            // logged in so return true
            return true;
        }

        // not logged in so redirect to login page with the return url
        this.router.navigate(['/login'], { queryParams: { returnUrl: state.url }});
        return false;
    }
}
 

Angular 6 Fake Backend Provider

Path: /src/app/_helpers/fake-backend.ts

The fake backend provider enables the example to run without a backend / backendless, I created it so I could focus the example and tutorial just on the angular code, and also so it works on StackBlitz.

It's implemented using the HttpInterceptor class that was introduced in Angular 4.3 as part of the new HttpClientModule. By extending the HttpInterceptor class you can create a custom interceptor to modify http requests before they get sent to the server. In this case the FakeBackendInterceptor intercepts certain requests based on their URL and provides a fake response instead of going to the server.

import { Injectable } from '@angular/core';
import { HttpRequest, HttpResponse, HttpHandler, HttpEvent, HttpInterceptor, HTTP_INTERCEPTORS } from '@angular/common/http';
import { Observable, of, throwError } from 'rxjs';
import { delay, mergeMap, materialize, dematerialize } from 'rxjs/operators';

@Injectable()
export class FakeBackendInterceptor implements HttpInterceptor {

    constructor() { }

    intercept(request: HttpRequest<any>, next: HttpHandler): Observable<HttpEvent<any>> {
        let testUser = { id: 1, username: 'test', password: 'test', firstName: 'Test', lastName: 'User' };

        // wrap in delayed observable to simulate server api call
        return of(null).pipe(mergeMap(() => {

            // authenticate
            if (request.url.endsWith('/api/authenticate') && request.method === 'POST') {
                if (request.body.username === testUser.username && request.body.password === testUser.password) {
                    // if login details are valid return 200 OK with a fake jwt token
                    return of(new HttpResponse({ status: 200, body: { token: 'fake-jwt-token' } }));
                } else {
                    // else return 400 bad request
                    return throwError({ error: { message: 'Username or password is incorrect' } });
                }
            }

            // get users
            if (request.url.endsWith('/api/users') && request.method === 'GET') {
                // check for fake auth token in header and return users if valid, this security is implemented server side in a real application
                if (request.headers.get('Authorization') === 'Bearer fake-jwt-token') {
                    return of(new HttpResponse({ status: 200, body: [testUser] }));
                } else {
                    // return 401 not authorised if token is null or invalid
                    return throwError({ error: { message: 'Unauthorised' } });
                }
            }

            // pass through any requests not handled above
            return next.handle(request);
            
        }))

        // call materialize and dematerialize to ensure delay even if an error is thrown (https://github.com/Reactive-Extensions/RxJS/issues/648)
        .pipe(materialize())
        .pipe(delay(500))
        .pipe(dematerialize());
    }
}

export let fakeBackendProvider = {
    // use fake backend in place of Http service for backend-less development
    provide: HTTP_INTERCEPTORS,
    useClass: FakeBackendInterceptor,
    multi: true
};
 

Angular 6 Http Error Interceptor

Path: /src/app/_helpers/error.interceptor.ts

The Error Interceptor intercepts http responses from the api to check if there were any errors. If there is a 401 Unauthorized response the user is automatically logged out of the application, all other errors are re-thrown to be caught by the calling service so an alert can be displayed to the user.

It's implemented using the HttpInterceptor class that was introduced in Angular 4.3 as part of the new HttpClientModule. By extending the HttpInterceptor class you can create a custom interceptor to catch all error responses from the server in a single location.

Http interceptors are added to the request pipeline in the providers section of the app.module.ts file.

import { Injectable } from '@angular/core';
import { HttpRequest, HttpHandler, HttpEvent, HttpInterceptor } from '@angular/common/http';
import { Observable, throwError } from 'rxjs';
import { catchError } from 'rxjs/operators';

import { AuthenticationService } from '../_services';

@Injectable()
export class ErrorInterceptor implements HttpInterceptor {
    constructor(private authenticationService: AuthenticationService) {}

    intercept(request: HttpRequest<any>, next: HttpHandler): Observable<HttpEvent<any>> {
        return next.handle(request).pipe(catchError(err => {
            if (err.status === 401) {
                // auto logout if 401 response returned from api
                this.authenticationService.logout();
                location.reload(true);
            }
            
            const error = err.error.message || err.statusText;
            return throwError(error);
        }))
    }
}
 

Angular 6 JWT Interceptor

Path: /src/app/_helpers/jwt.interceptor.ts

The JWT Interceptor intercepts http requests from the application to add a JWT auth token to the Authorization header if the user is logged in.

It's implemented using the HttpInterceptor class that was introduced in Angular 4.3 as part of the new HttpClientModule. By extending the HttpInterceptor class you can create a custom interceptor to modify http requests before they get sent to the server.

Http interceptors are added to the request pipeline in the providers section of the app.module.ts file.

import { Injectable } from '@angular/core';
import { HttpRequest, HttpHandler, HttpEvent, HttpInterceptor } from '@angular/common/http';
import { Observable } from 'rxjs';

@Injectable()
export class JwtInterceptor implements HttpInterceptor {
    intercept(request: HttpRequest<any>, next: HttpHandler): Observable<HttpEvent<any>> {
        // add authorization header with jwt token if available
        let currentUser = JSON.parse(localStorage.getItem('currentUser'));
        if (currentUser && currentUser.token) {
            request = request.clone({
                setHeaders: { 
                    Authorization: `Bearer ${currentUser.token}`
                }
            });
        }

        return next.handle(request);
    }
}
 

Angular 6 User Model

Path: /src/app/_models/user.ts

The user model is a small class that defines the properties of a user.

export class User {
    id: number;
    username: string;
    password: string;
    firstName: string;
    lastName: string;
}
 

Angular 6 JWT Authentication Service

Path: /src/app/_services/authentication.service.ts

The JWT authentication service is used to login and logout of the application, to login it posts the users credentials to the api and checks the response for a JWT token, if there is one it means authentication was successful so the user details are added to local storage and the token saved to the AuthenticationService.token property. The token property is used by other services in the application to set the authorization header of http requests made to secure api endpoints.

The logged in user details are stored in local storage so the user will stay logged in if they refresh the browser and also between browser sessions until they logout. If you don't want the user to stay logged in between refreshes or sessions the behaviour could easily be changed by storing user details somewhere less persistent such as session storage or in a property of the authentication service.

import { Injectable } from '@angular/core';
import { HttpClient } from '@angular/common/http';
import { map } from 'rxjs/operators';

@Injectable({ providedIn: 'root' })
export class AuthenticationService {
    constructor(private http: HttpClient) { }

    login(username: string, password: string) {
        return this.http.post<any>('/api/authenticate', { username: username, password: password })
            .pipe(map((res:any) => {
                // login successful if there's a jwt token in the response
                if (res && res.token) {
                    // store username and jwt token in local storage to keep user logged in between page refreshes
                    localStorage.setItem('currentUser', JSON.stringify({ username, token: res.token }));
                }
            }));
    }

    logout() {
        // remove user from local storage to log user out
        localStorage.removeItem('currentUser');
    }
}
 

Angular 6 User Service

Path: /src/app/_services/user.service.ts

The user service contains a method for getting all users from the api, I included it to demonstrate accessing a secure api endpoint with the http authorization header set after logging in to the application, the auth header is set with a JWT token with the JWT Interceptor above. The secure endpoint in the example is a fake one implemented in the fake backend provider above.

import { Injectable } from '@angular/core';
import { HttpClient } from '@angular/common/http';

import { User } from '../_models';

@Injectable({ providedIn: 'root' })
export class UserService {
    constructor(private http: HttpClient) { }

    getAll() {
        return this.http.get<User[]>('/api/users');
    }
}
 

Angular 6 Home Component Template

Path: /src/app/home/home.component.html

The home component template contains html and angular 6 template syntax for displaying a simple welcome message, a list of users and a logout link.

<h1>Home</h1>
<p>You're logged in with Angular 6 & JWT!!</p>
<div>
    Users from secure api end point:
    <ul>
        <li *ngFor="let user of users">{{user.firstName}} {{user.lastName}}</li>
    </ul>
</div>
<p><a [routerLink]="['/login']">Logout</a></p>
 

Angular 6 Home Component

Path: /src/app/home/home.component.ts

The home component defines an angular 6 component that gets all users from the user service and makes them available to the template via a users array property.

import { Component, OnInit } from '@angular/core';
import { first } from 'rxjs/operators';

import { User } from '../_models';
import { UserService } from '../_services';

@Component({templateUrl: 'home.component.html'})
export class HomeComponent implements OnInit {
    users: User[] = [];

    constructor(private userService: UserService) {}

    ngOnInit() {
        this.userService.getAll().pipe(first()).subscribe(users => { 
            this.users = users; 
        });
    }
}
 

Angular 6 Login Component Template

Path: /src/app/login/login.component.html

The login component template contains a login form with username and password fields. It displays validation messages for invalid fields when the submit button is clicked. The form submit event is bound to the onSubmit() method of the login component.

The component uses reactive form validation to validate the input fields, for more information about angular reactive form validation check out Angular 6 - Reactive Forms Validation Example.

<div class="alert alert-info">
    Username: test<br />
    Password: test
</div>
<h2>Login</h2>
<form [formGroup]="loginForm" (ngSubmit)="onSubmit()">
    <div class="form-group">
        <label for="username">Username</label>
        <input type="text" formControlName="username" class="form-control" [ngClass]="{ 'is-invalid': submitted && f.username.errors }" />
        <div *ngIf="submitted && f.username.errors" class="invalid-feedback">
            <div *ngIf="f.username.errors.required">Username is required</div>
        </div>
    </div>
    <div class="form-group">
        <label for="password">Password</label>
        <input type="password" formControlName="password" class="form-control" [ngClass]="{ 'is-invalid': submitted && f.password.errors }" />
        <div *ngIf="submitted && f.password.errors" class="invalid-feedback">
            <div *ngIf="f.password.errors.required">Password is required</div>
        </div>
    </div>
    <div class="form-group">
        <button [disabled]="loading" class="btn btn-primary">Login</button>
        <img *ngIf="loading" src="data:image/gif;base64,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" />
    </div>
    <div *ngIf="error" class="alert alert-danger">{{error}}</div>
</form>
 

Angular 6 Login Component

Path: /src/app/login/login.component.ts

The login component uses the authentication service to login and logout of the application. It automatically logs the user out when it initializes (ngOnInit) so the login page can also be used to logout.

The loginForm: FormGroup object defines the form controls and validators, and is used to access data entered into the form. The FormGroup is part of the Angular Reactive Forms module and is bound to the login template above with the [formGroup]="loginForm" directive.

import { Component, OnInit } from '@angular/core';
import { Router, ActivatedRoute } from '@angular/router';
import { FormBuilder, FormGroup, Validators } from '@angular/forms';
import { first } from 'rxjs/operators';

import { AuthenticationService } from '../_services';

@Component({templateUrl: 'login.component.html'})
export class LoginComponent implements OnInit {
    loginForm: FormGroup;
    loading = false;
    submitted = false;
    returnUrl: string;
    error = '';

    constructor(
        private formBuilder: FormBuilder,
        private route: ActivatedRoute,
        private router: Router,
        private authenticationService: AuthenticationService) {}

    ngOnInit() {
        this.loginForm = this.formBuilder.group({
            username: ['', Validators.required],
            password: ['', Validators.required]
        });

        // reset login status
        this.authenticationService.logout();

        // get return url from route parameters or default to '/'
        this.returnUrl = this.route.snapshot.queryParams['returnUrl'] || '/';
    }

    // convenience getter for easy access to form fields
    get f() { return this.loginForm.controls; }

    onSubmit() {
        this.submitted = true;

        // stop here if form is invalid
        if (this.loginForm.invalid) {
            return;
        }

        this.loading = true;
        this.authenticationService.login(this.f.username.value, this.f.password.value)
            .pipe(first())
            .subscribe(
                data => {
                    this.router.navigate([this.returnUrl]);
                },
                error => {
                    this.error = error;
                    this.loading = false;
                });
    }
}
 

Angular 6 App Component Template

Path: /src/app/app.component.html

The app component template is the root component template of the application, it contains a router-outlet directive for displaying the contents of each view based on the current route / path.

<!-- main app container -->
<div class="jumbotron">
    <div class="container">
        <div class="row">
            <div class="col-sm-6 offset-sm-3">
                <router-outlet></router-outlet>
            </div>
        </div>
    </div>
</div>
 

Angular 6 App Component

Path: /src/app/app.component.ts

The app component is the root component of the application, it defines the root tag of the app as <app></app> with the selector property.

import { Component } from '@angular/core';

@Component({
    selector: 'app',
    templateUrl: 'app.component.html'
})

export class AppComponent { }
 

Angular 6 App Module

Path: /src/app/app.module.ts

The app module defines the root module of the application along with metadata about the module. For more info about angular 6 modules check out this page on the official docs site.

This is where the fake backend provider is added to the application, to switch to a real backend simply remove the providers located below the comment // provider used to create fake backend.

import { NgModule }      from '@angular/core';
import { BrowserModule } from '@angular/platform-browser';
import { ReactiveFormsModule }    from '@angular/forms';
import { HttpClientModule, HTTP_INTERCEPTORS } from '@angular/common/http';

// used to create fake backend
import { fakeBackendProvider } from './_helpers';

import { AppComponent }  from './app.component';
import { routing }        from './app.routing';

import { JwtInterceptor, ErrorInterceptor } from './_helpers';
import { HomeComponent } from './home';
import { LoginComponent } from './login';

@NgModule({
    imports: [
        BrowserModule,
        ReactiveFormsModule,
        HttpClientModule,
        routing
    ],
    declarations: [
        AppComponent,
        HomeComponent,
        LoginComponent
    ],
    providers: [
        { provide: HTTP_INTERCEPTORS, useClass: JwtInterceptor, multi: true },
        { provide: HTTP_INTERCEPTORS, useClass: ErrorInterceptor, multi: true },

        // provider used to create fake backend
        fakeBackendProvider
    ],
    bootstrap: [AppComponent]
})

export class AppModule { }
 

Angular 6 App Routing

Path: /src/app/app.routing.ts

The app routing file defines the routes of the application, each route contains a path and associated component. The home route is secured by passing the AuthGuard to the canActivate property of the route.

import { Routes, RouterModule } from '@angular/router';

import { HomeComponent } from './home';
import { LoginComponent } from './login';
import { AuthGuard } from './_guards';

const appRoutes: Routes = [
    { path: '', component: HomeComponent, canActivate: [AuthGuard] },
    { path: 'login', component: LoginComponent },

    // otherwise redirect to home
    { path: '**', redirectTo: '' }
];

export const routing = RouterModule.forRoot(appRoutes);
 

Angular 6 Main Index Html File

Path: /src/index.html

The main index.html file is the initial page loaded by the browser that kicks everything off. Webpack bundles all of the javascript files together and injects them into the body of the index.html page so the scripts get loaded and executed by the browser.

<!DOCTYPE html>
<html>
<head>
    <base href="/" />
    <title>Angular 6 JWT Authentication Example</title>
    <meta name="viewport" content="width=device-width, initial-scale=1">

    <!-- bootstrap css -->
    <link href="//netdna.bootstrapcdn.com/bootstrap/4.1.1/css/bootstrap.min.css" rel="stylesheet" />

    <style>
        a { cursor: pointer }
    </style>
</head>
<body>
    <app>Loading...</app>
</body>
</html>
 

Angular 6 Main (Bootstrap) File

Path: /src/main.ts

The main file is the entry point used by angular to launch and bootstrap the application.

import './polyfills';

import { platformBrowserDynamic } from '@angular/platform-browser-dynamic';
import { AppModule } from './app/app.module';
platformBrowserDynamic().bootstrapModule(AppModule);
 

Angular 6 Polyfills

Path: /src/polyfills.ts

Some features used by Angular 6 are not yet supported natively by all major browsers, polyfills are used to add support for features where necessary so your Angular 6 application works across all major browsers.

import 'core-js/es6/reflect';
import 'core-js/es7/reflect';
import 'zone.js/dist/zone';
 

npm package.json

Path: /package.json

The package.json file contains project configuration information including package dependencies which get installed when you run npm install. Full documentation is available on the npm docs website.

{
  "name": "angular-6-jwt-authentication-example",
  "version": "1.0.0",
  "repository": {
    "type": "git",
    "url": "https://github.com/cornflourblue/angular-6-jwt-authentication-example.git"
  },
  "scripts": {
    "build": "webpack --mode production",
    "start": "webpack-dev-server --mode development --open"
  },
  "license": "MIT",
  "dependencies": {
    "@angular/common": "^6.0.0",
    "@angular/compiler": "^6.0.0",
    "@angular/core": "^6.0.0",
    "@angular/forms": "^6.0.0",
    "@angular/platform-browser": "^6.0.0",
    "@angular/platform-browser-dynamic": "^6.0.0",
    "@angular/router": "^6.0.0",
    "core-js": "^2.5.5",
    "rxjs": "^6.1.0",
    "zone.js": "^0.8.26"
  },
  "devDependencies": {
    "@types/node": "^10.0.4",
    "angular2-template-loader": "^0.6.2",
    "html-webpack-plugin": "^3.2.0",
    "raw-loader": "^0.5.1",
    "ts-loader": "^4.3.0",
    "typescript": "^2.8.3",
    "webpack": "4.8.1",
    "webpack-cli": "^2.1.3",
    "webpack-dev-server": "3.1.4"
  }
}
 

TypeScript tsconfig.json

Path: /tsconfig.json

The tsconfig.json file configures how the TypeScript compiler will convert TypeScript into JavaScript that is understood by the browser. More information is available on the TypeScript docs.

{
  "compilerOptions": {
    "emitDecoratorMetadata": true,
    "experimentalDecorators": true,
    "lib": [ "es2015", "dom" ],
    "module": "commonjs",
    "moduleResolution": "node",
    "noImplicitAny": true,
    "sourceMap": true,
    "suppressImplicitAnyIndexErrors": true,
    "target": "es5"
  }
}
 

Webpack 4 Config

Path: /webpack.config.js

Webpack 4.8 is used to compile and bundle all the project files so they're ready to be loaded into a browser, it does this with the help of loaders and plugins that are configured in the webpack.config.js file. For more info about webpack check out the webpack docs.

This is a minimal webpack.config.js for bundling an Angular 6 application, it compiles TypeScript files using ts-loader, loads angular templates with raw-loader, and injects the bundled scripts into the body of the index.html page using the HtmlWebpackPlugin.

const HtmlWebpackPlugin = require('html-webpack-plugin');

module.exports = {
  entry: './src/main.ts',

  module: {
    rules: [
      {
        test: /\.ts$/,
        use: ['ts-loader', 'angular2-template-loader'],
        exclude: /node_modules/
      },
      {
        test: /\.(html|css)$/,
        loader: 'raw-loader'
      },
    ]
  },
  
  resolve: {
    extensions: ['.ts', '.js']
  },

  plugins: [
    new HtmlWebpackPlugin({
      template: './src/index.html',
      filename: 'index.html',
      inject: 'body'
    })
  ],

  optimization: {
    splitChunks: {
      chunks: 'all',
    },
    runtimeChunk: true
  },

  devServer: {
    historyApiFallback: true
  }
};

 

Web Development Sydney

Feel free to contact me if you're looking for a web developer in Sydney, I also provide remote contracting services for clients outside Sydney.


Sponsored by