Learn Eslint, Jwt and Nightmare

This playlist will be a smorgasbord of Auth0 authentication and authorization topics. Everything from adding Auth0 to various apps, customizing your Auth0 settings, adding specific rules / audiences / features, and debugging errors. 

JavaScript® (often shortened to JS) is a lightweight, interpreted, object-oriented language with first-class functions, most known as the scripting language for Web pages, but used in many non-browser environments as well such as node.js or Apache CouchDB. It is a prototype-based, multi-paradigm scripting language that is dynamic, and supports object-oriented, imperative, and functional programming styles.

javascript

Auth0 Tips and Tricks 

JSON Web Token (JWT) is a low overhead option for authentication that is easy to implement and scales with your application. There is no need to store session data as everything you need is stored in an encoded string sent in the JWT, significantly reducing database overhead for your servers.

In this course, we will build a simple authentication server that will act as a token issuer, and we will use those tokens to access resources on an API.  Starting from scratch, you will learn how easy token based authentication can be and will understand how to use them on your APIs as well as on the front end of your web applications.

Express is a minimal and flexible Node.js web application framework that provides a robust set of features for web and mobile applications.

express

JSON Web Token (JWT) Authentication with Node.js and Auth0

JSON Web Tokens (JWT) are a more modern approach to authentication. As the web moves to a greater separation between the client and server, JWT provides a terrific alternative to traditional cookie based authentication models. For more information on JWT visit http://jwt.io/

In this series, we’ll be building a simple application to get random user information from a node server with an Angular client. We’ll then implement JWT to protect the random user resource on the server and then work through the frontend to get JWT authentication working.

By the end, we’ll have an application which has a single username/password combination (for simplicity) and uses tokens to authorize the client to see the random user information. You’ll be able to login, get random users, and logout.

AngularJS is an open-source JavaScript framework, maintained by Google, that assists with running single-page applications. Its goal is to augment web-based applications with model–view–controller (MVC) capability, in an effort to make both development and testing easier.

angularjs

AngularJS Authentication with JWT

React is one of the web’s most popular frameworks for building JavaScript applications. 

If you know what you’re doing, React can drastically simplify how you build, use, and maintain code.

Whether you’re a React newbie or you’re ready for advanced techniques, you can level-up with egghead. Explore our in-depth courses, lessons, and community resources to build more powerful applications and crack open your career.

react

Our first layer of defense when building accessible React applications is to add some auditing tools to our development workflow. This should include adding static analysis checking for common accessibility standards and best practices. We can get this with the latest eslint plugin: "eslint-plugin-jsx-a11y". If you are already linting your projects adding this plugin should fit very smoothly into your workflow.

## Resources
1. [List of all the rules supported by eslint-plugin-jsx-a11y](https://github.com/evcohen/eslint-plugin-jsx-a11y#supported-rules)
2. [Comparison of the difference in rules between recommended and strict mode](https://github.com/evcohen/eslint-plugin-jsx-a11y#difference-between-recommended-and-strict-mode)
3. [Background on how the Accessibility API implemented by browsers interfaces with Assistive Technologies](https://github.com/evcohen/eslint-plugin-jsx-a11y#some-background-on-wai-aria-the-ax-tree-and-browsers)

Set up ESLint to Audit Accessibility Issues in React

The pluggable linting utility for JavaScript and JSX.

eslint

We have a number of options to use when testing for accessibility issues concerning alternative text for images.  The react-axe library and axe browser extension will both report when an image is missing alternative text.  The tota11y browser extension will annotate any images that are missing alternative text.  Running eslint with the eslint-plugin-jsx-a11y plugin installed will report on any `<img>` elements missing an `alt` attribute.  Finally, we can use a screen reader to actually hear what is read when an image has focus.

Test for Image Alternative Text Accessibility Issues

Images must have text alternatives that describe the information or function 
represented by them so they can be read and understood by those using screen readers.

## Alternative text for images
* All `<img>` elements should have an `alt` attribute provided
    * When not provided many screen readers will fallback to reading the file name instead
* The `alt` value should not include words like _“image”_, _“picture”_ or _“icon”_
    * Screen readers are already announcing that the element is an image
* Images that are decorative only and provide no information or function to the page should be hidden from Assistive Technologies by providing an empty `alt` attribute (`alt=””`)

## References
* https://www.w3.org/WAI/tutorials/images/
* https://www.w3.org/WAI/tutorials/images/decision-tree/
* https://www.w3.org/WAI/tutorials/images/tips/
* https://www.w3.org/WAI/tutorials/images/informative/
* https://www.w3.org/WAI/tutorials/images/functional/
* https://www.w3.org/WAI/tutorials/images/textual/

Define Images with Appropriate Text Alternatives

Our accessibility auditing toolkit makes it very easy for us to test for any form controls that are missing labels or are not correctly associated with their labels.  Running Eslint with the eslint-plugin-jsx-a11y installed will show us any form controls with missing or unassociated labels.  Running react-axe or using axe to audit a web page will similarly list any of these findings.  Finally using tota11y we can annotate any form controls on a page that are missing labels.  This is definitely some of the lower hanging fruit that we can easily find and fix when making our applications accessible!

Test for Form Control Label Accessibility Issues

Labeling inputs, elements, and widgets add context and clarity for assistive technology such as screen readers.  Elements of a `<form>` such as `<input>` or `<textarea>` or `<select>` should be labelled by using a `<label>` element.  Placeholder text can be used in addition to a label but should not be used in place of a label as not all assistive technologies respect placeholder text.

Ensure Form Controls have Accessible Labels

In this lesson you will learn how to use the eslint yeoman generator to scaffold a new plugin to provide custom rules for your project. 
You will also be able to check the basic skeleton for an eslint ruleand a working example rule to apply a naming convention for async functions.

Scaffold an eslint Plugin with Yeoman

Authentication and authorization doesn't need to be hard. In this lesson, we're going to use the Auth0 React SDK to add authentication to protect a route. Which means that a user has to be logged in in order to access any content on that page. We'll finish the lesson by sending an access token to an Express API in order to retrieve some data. 

Protecting Routes and Calling Secure APIs in React with Auth0

With Auth0's React SDK, integreting an identity provider has never been easier. With a couple changes to your React app, creating an account within Auth0, we can have a login experience ready to go! This lesson will walk through all the steps nesscary such as adding the SDK through npm, setting up your Auth0 account, adding a login/logout button, and using the Auth0 provided hook to access values. 

Adding Login to React with Auth0

In this lesson, we will use Auth0 to generate a JWT that we can use to validate future requests to our server.

We will then return that token and test that it works when authenicated by our middleware.

During the lesson, we'll also briefly look at a strategy to keep your credentials out of source control using a .gitignore file. 

Get a JWT From Auth0 in Express to Be Used in Authentication

Sending a JSON Web Token is one way to valid your identity as a user of an API or service. In this lesson, we will see how to add an Express middleware which will check for a valid JWT and return a 401 Unauthorized error if not.

Add Middleware to Validate a JSON Web Token (JWT)

Nx already comes with a default TypeScript setup. Although you can opt-out of that and generate plain JS based components, especially in a large setup TypeScript can be beneficial in uncovering potential issues early. To add an extra level, Nx also comes with preconfigured eslint for all the apps and libraries. In this lesson we're going to explore the lint setup and how it can be used.

Linting a React app with Nx

JSON Web Tokens are an open, industry standard RFC 7519 method for representing claims securely between two parties.

In simple terms, authorization is the process of verifying what users have access to (after authenticating). This video assumes that you already have authentication set up and are ready to add authorization. 

Authentication is the process of verifying if a user is who they say they are. After a user successfully authenticates, access JWTs are issued back to the application. 

In our case of authorization, we are using the JWT (JSON web token) in our NodeJS / ExpressJS API calls, to verify the user has the correct access to the desired resource. 

Authorization in NodeJS with ExpressJS and JWT

Role-Based Access Control (RBAC) is the idea of grouping permissions together by a role. Users are assigned a role through the Auth0 dashboard the corresponding permissions are placed on the user's access token (JWT) after authenticating. That access token can be extracted by an Auth0 SDK (this video uses JavaScipt/ ReactJS) and sent to a custom server. 

Server Side logic (this video is based on NodeJS and ExpressJS), can then check for specific permissions and then allow or reject certain resources. 

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Starting point- https://github.com/twclark0/roles-scopes-node-auth0/tree/roles-beginning

Ending point- https://github.com/twclark0/roles-scopes-node-auth0/tree/roles-final

Role Based Auth in NodeJS with ExpressJS and Auth0

Universal Login is Auth0's implementation of the login flow, which is the key feature of an Authorization Server. Each time a user needs to prove their identity, your applications redirect to Universal Login and Auth0 will do what is needed to guarantee the user's identity.

This video will walk you through how to customize and brand the Universal Login experience. This includes setting a custom domain, styling the user emails, and add your company logo to the form. 

Customize the Auth0 Universal Login

Adding middleware to the node server to decode and verify the token sent from the client. And tidying up the rest of the application. Finally, a walkthrough of the whole process.

Finalizing JWT Authentication with AngularJS

Creating the basic node server to serve up random users via API endpoints.

Basic Server Setup for JWT Authentication

Adding JWT support to the client. Storing the token in local storage, then creating a http interceptor to add the token to requests made to the server. Also implementing logout.


Auth Interceptor in Angular for JWT

A basic introduction to the mechanics of JWTs and the application we will be building in this lesson series.

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