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

In this lesson we will look at all of the pieces that combine together to create a JWT (j AWT) or JSON Web Token. You will use node to create a JWT, and then verify it in the JWT debugger.

Creating JWTs (JSON Web Tokens) in Node

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

ESLint is a JavaScript linter (static analysis tool) that offers full support for ES6, JSX, and other modern tools via plugins. We walk through setting up ESLint in a project, using the `eslint --init` CLI tool with the JSX and ES6 options, writing a React component in JSX, and adding some extra react linting rules with a plugin. ESLint is built to be "pluggable" with simple, extendable, modular rules and an API for writing and using plugins. ESLint has many rules which are all turned off by default; you can extend the core "recommended" rules which will catch common JavaScript errors, and you can also turn on stylistic rules for code consistency. You can also use plugin rules which we do in this lesson with the `eslint-plugin-react` package.

Linting React JSX with ESLint (in ES6)

Nightmare is a high-level browser automation library.

The goal is to expose just a few simple methods, and have an API that feels synchronous for each block of scripting, rather than deeply nested callbacks. It's designed for automating tasks across sites that don't have APIs.

nightmare

Many pages you'll want to grab data from will require you to log in first. This video demonstrates how to log in and grab whatever data off the page you will need.

Scraping Data from Sites with Login Forms with Nightmare

Many websites have more than just simple static content. Dynamic content which is rendered by JavaScript requires browser to be able to scrape data. This video demonstrates how to use Nightmare (which is a wrapper around Electron) to launch a url and scrape dynamic data.

Scraping Dynamic JavaScript Websites with Nightmare

Nuclide is the IDE Facebook employees use to write React code. But setting it up to use Flow type checking and Eslint to lint files on the fly is tricky. This video shows you how. 

Setup Nuclide to use Flow and Eslint (Mac)

The pluggable linting utility for JavaScript and JSX.

eslint

ESLint is a JavaScript linter (static analysis tool) that offers full support for ES6, JSX, and other modern tools via plugins. We walk through setting up ESLint in a project, using the "init" CLI tool, configuring warnings/errors for rules, and adding editor plugins and build integrations. ESLint is built to be "pluggable" with simple, extendable, modular rules and an API for writing and using plugins. ESLint has many rules which are all turned off by default; you can extend the core "recommended" rules which will catch common JavaScript errors, and you can also turn on stylistic rules for code consistency.

Linting JavaScript with ESLint

This lesson will digitally sign the IBM Domino user information into a JWT which can then be sent from the server to the client.

This JWT can then be sent back from the client to the server and the role information within the JWT file can be decrypted to determine a users level of functional access.

Encrypt IBM Domino User Roles Data into a JWT in a Express Application

This lesson will take the JWT sent from Express and store it in the browser local storage.  It will then resend the JWT back to the Express server when a HTTP call is made for additional IBM Domino Data.

This stateless method allows the server to trust what user roles the logged in user has to restrict what Express routes the user can call.  For instance you might want to restrict all Admin routes to only users which have the Admin role in the Domino ACL.

Send JWT Encrypted User Role Data from Client Local Storage to Express Server

This lesson will extract the JWT from the authorisation HTTP header and then decode it with the secret.

It will then check to make sure it contains a specific user role value to determine if a specific route can be called in Express.

Decode and Verify JWT Encoded Data in Express

JavaScript is great! JavaScript is also full of features and flexible options that can make it easy to introduce bugs. ESLint uses static analysis to check that your code adheres to a list of rules to help you avoid some specific runtime errors. ESLint is highly configurable, so in this lesson, we'll install ESLint and configure some baseline rules for our boilerplate.

Avoid Common JavaScript Errors with ESLint 

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

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

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.

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