Learn A11y, Angularfire and Browserify

- Web audio APIs include support for features that aren't available by default in the native HTML audio element.
- The operating system includes basic controls
- Custom controls must be accessible with a keyboard, and make sense to a screen reader
- Don't hide the built-in controls until you know that your custom controls are working
- Listening to what VoiceOver reads should inform the a11y information you include
    - VoiceOver says "Elapsed Time" on its own, so we wouldn't want to write it in our code.
- `loadedmetadata` should have the duration to avoid glitches from new audio not being loaded.
- Elements should be labeled with a unique `id`

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

Create an Accessible Audio Player with the HTML Media Element and React

Web accessibility (also referred to as a11y) is the design and creation of websites that can be used by everyone. Accessibility support is necessary to allow assistive technology to interpret web pages.

React fully supports building accessible websites, often by using standard HTML techniques.

Erin Doyle is an expert in creating accessible React applications and has developed a course that will give you a concrete process for auditing react apps for accessibility. In this course, you will go through different tools and libraries to audit components in a React app.

Fast, easy and reliable testing for anything that runs in a browser.

cypress

Auditing React Apps for Accessibility 

Gulp is a toolkit for automating painful or time-consuming tasks in your development workflow, so you can stop messing around and build something.

gulp

Building upon the `watch` task that we begin this lesson with, we’ll look at how to create a local development server using the `app` directory as the web root. By using Browsersync to achieve this, we can also instruct all connected browsers to automatically reload each time our bundle is re-generated. Browsersync has a public `.stream()` method that is designed exactly for this purpose.

Gulp and Browserify - Adding Live Reload with Browsersync

Babel has support for the latest version of JavaScript through syntax transformers. These plugins allow you to use new syntax, right now without waiting for browser support.

babel

What is already a nice workflow using Gulp, Browserify, Watchify & Browsersync to enable auto rebuilds & live browser reloading can be further improved by adding Babelify. A simple wrapper around the popular transpiler Babel, Babelify can ‘transform’ source files as they pass through our stream to enable certain Javascript features not yet available in the Browser or Node. We end the lesson by looking at how to generate & extract sourcemaps using `exorcist`.

Gulp and Browserify - Adding Babel & Source Maps

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

Firebase provides a real-time syncing backend for your AngularJS applications in very few lines of code. In this lesson, you'll learn how to get started integrating it into your app.

Get Started with Firebase and AngularFire

Browserify lets you require('modules') in the browser by bundling up all of your dependencies.

browserify

Let's look at the basics of setting up Gulp and Browserify. Creating a Gulp task from scratch, we'll cover how to utilise the Browserify API to generate a single `bundle.js` file, catch and log any errors that occur in the compilation process, transform the stream into a format that can be consumed by `gulp.dest` and finish by writing the bundle to a `dist` directory.

Gulp and Browserify - Initial Setup

Beginning with a single Gulp task capable of generating a one-time Browserify bundle, we enable file-watching and incremental rebuilds by incorporating Watchify. We add a second task `watch` & refactor our initial code to enable the bulk of it to be re-used. We’ll look at exactly how to ‘wire’ these tools together and how the relationship between Watchify & Browserify can manifest into a seriously efficient workflow.

Gulp and Browserify - Hooking up Watchify

Building a component library is a great way to gain efficiencies in creating accessible React apps and Storybook is a great tool for doing that. Using the accessibility add-on to Storybook you can test your components in isolation for accessibility issues before composing them into an application.

If you can write and test each of these components initially with accessibility in mind then you now have:

* A library of reusable components with accessibility baked in.
* You won’t need to solve the same problems over and over again.

## Resources
* https://storybook.js.org/
* https://www.npmjs.com/package/@storybook/addon-a11y

Audit Component Accessibility Using Storybook

AngularFire is the officially supported AngularJS binding for Firebase. Firebase is a backend service that provides data storage, file storage, authentication, and static website hosting for your Angular app.

angularfire

You'll learn the 2 Observables that Firebase Authentication provides to subscribe to the authentication state of your application, `authState` and `user`.

You'll see how they both return the same `User` object from Firebase Authentication.

And you'll learn that the difference is that `authState` triggers when the user logs in, or logs out of the application, while `user` is called both of those times, and also is called when Firebase refreshes the user's authentication token.

As a personal guideline, if I need to do an operation when the user's token is refreshed (_for example, update a 3rd party service_) I'll use `user`, if not, I'll default to `authState`.

Choose Between authState or user to Subscribe to Firebase Authentication State Changes

We can add accessibility testing to our `jest` unit tests with `jest-axe` which gives us:

* An easy way to automate accessibility auditing.
* The flexibility to audit at any level of our code, as low as an element and as high as a component representing an entire page of our app.
* A safety net for any accessibility regressions.

Here we'll see how to use `jest-axe` with `ReactDOM` to render components for `jest-axe` to audit for accessibility.

## Resources
* https://github.com/nickcolley/jest-axe

Render Components with ReactDOM to Write Tests with Jest and jest-axe

“a11y” stands for “accessibility.” It is a numeronym, with 11 representing the count of letters between the letter a and the letter y.

Accessibility is broken down into 4 categories of disability: visual, cognitive, auditory, motor. 

Regardless of the category of disability, accessibilities aim in web development is to make applications and websites usable for everyone.

a11y

To automate running Lighthouse audits on our application we can add the use of the Lighthouse CI tool to our Continuous Integration suite using GitHub Actions.  By making use of the Lighthouse CI GitHub App we can add to the checks in every Pull Request a report with the score from the audit run on each URL we configure for Lighthouse to audit.

## Resources
* https://github.com/GoogleChrome/lighthouse-ci/blob/main/docs/getting-started.md
* https://github.com/GoogleChrome/lighthouse-ci/blob/main/docs/configuration.md
* https://github.com/apps/lighthouse-ci

Automate Lighthouse Audits with GitHub Actions

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

You’ve probably heard of Lighthouse before as it comes bundled with Chrome DevTools for performing a number of audits on things such as performance, SEO, best practices as well as accessibility. 

We can also use Lighthouse locally on our machines to test our application's rendered pages for accessibility issues before committing changes by using the Lighthouse CI CLI.

## Resources
* https://github.com/GoogleChrome/lighthouse-ci
* https://github.com/GoogleChrome/lighthouse-ci/blob/main/docs/configuration.md

Audit an App's Rendered Pages Locally with Lighthouse CI CLI

The pluggable linting utility for JavaScript and JSX.

eslint

We can leverage GitHub Actions to automate the running of all of our accessibility auditing tools as part of a Continuous Integration (CI) workflow. 

Auditing tools will only catch a percentage of potential accessibility issues, it is no replacement for manual testing.  But being able to automate the auditing will add efficiencies to our testing and provide an early warning system that can be run much more frequently than it’s practical to perform manual testing.  Additionally, we can use our CI suite as a safety net to prevent code changes that break accessibility from being able to be merged.

## Resources
* https://app.egghead.io/lessons/react-set-up-eslint-to-audit-accessibility-issues-in-react
* https://docs.cypress.io/guides/continuous-integration/github-actions#Basic-Setup
* https://github.com/cypress-io/github-action

Automate Accessibility Audits with GitHub Actions

To audit our app for accessibility issues at runtime we can use Cypress to run our application in a browser environment and then with the aid of the axe-core `cypress-axe` library we can analyze the current page for any accessibility issues.

## Resources
* https://www.cypress.io/
* https://github.com/component-driven/cypress-axe
* https://mochajs.org/#bdd
* https://www.chaijs.com/guide/styles/

Write E2E Tests for Accessibility Using aXe-core and Cypress

To audit our app for accessibility issues at runtime we can use Selenium WebDriver to run our application in a browser environment and then with the aid of the aXe-core `webdriverjs` library we can analyze the current page for any accessibility issues.

## Resources
* https://www.selenium.dev/documentation/getting_started/installing_browser_drivers/
* https://github.com/dequelabs/axe-core-npm/blob/develop/packages/webdriverjs/README.md 

Test Accessibility at Runtime with Selenium WebDriver and aXe-Core

We can add accessibility testing to our `jest` unit tests with `jest-axe` which gives us:

* An easy way to automate accessibility auditing
* the flexibility to audit at any level of our code, as low as an element and as high as a component representing an entire page of our app
* A safety net for any accessibility regressions

Here we'll see how to use `jest-axe` with `react-testing-library` to render the components for `jest-axe` to audit for accessibility.

The React Testing Library is a very light-weight solution for testing React components. It provides light utility functions on top of react-dom and react-dom/test-utils, in a way that encourages better testing practices.

## Resources
* jest-axe: https://github.com/nickcolley/jest-axe
* react-testing-library: https://testing-library.com/docs/react-testing-library/intro/

Write Better Unit Tests with react-testing-library and jest-axe

We can add accessibility testing to our `jest` unit tests with `jest-axe` which gives us:

* An easy way to automate accessibility auditing.
* The flexibility to audit at any level of our code, as low as an element and as high as a component representing an entire page of our app.
* A safety net for any accessibility regressions.

Here we'll see how to use `jest-axe` with `enzyme` to render the components for `jest-axe` to audit for accessibility.

Enzyme is a JavaScript Testing utility for React that makes it easier to test your React Components' output. You can also manipulate, traverse, and in some ways simulate runtime given the output.

## Resources
* jest-axe: https://github.com/nickcolley/jest-axe
* enzyme: https://enzymejs.github.io/enzyme

Write Unit Tests for Accessibility Using jest-axe and enzyme

We are creating an accessible popup menu for a web application. It covers various concepts, including handling keyboard events, creating a new dropdown component for reuse, using arrow keys to navigate through buttons, using the Tab key to close the menu and go to the next item in the tab order, using the Escape key to close the menu and focus on the button that closes it, using the `aria-expanded` attribute to communicate whether the menu is open or closed, and the difference between the tab index values of 0 and -1. 

**Think about:**
- Why tabindex -1?
- Why would you use arrows versus tab key to navigate through the dropdown?

Create a Dropdown Menu for Rates

In this lesson, we are using HTML, accessibility concepts, and ARIA attributes to improve the time scrubber feature of an audio player. 

The goal is to make it accessible to users of screen readers so that the time scrubber announces the actual time (e.g. 12 minutes and 15 seconds) rather than just the value (e.g. 735). 

We are also creating a new folder called "helpers" in the "src" folder and a new file called "format time.js" within it to hold a function called "format human read time" that takes time as a parameter and returns the human-readable equivalent of that time. Additionally, the author debugs the code and uses console.log to check the variable.

**Think about:** Why does a human-readable name help?

Create a Human Readable Time Formatter

I suggest using the previously learned approach but keep in mind that it may lead to an overly complex markup. We also use the `aria-label` attribute, which can be used to override the text within a label element.

**Think about:** Why would you use an `aria-label` instead of creating a visually hidden span?

Using Aria-Label as a Solution for Overly Complex Markup

We create an input range with a label, where the range is between 0 and 1 with a step of 0 - 1. The input's value should be determined by a ternary statement that checks if the volume is muted and sets it to 0 or to the current volume if not muted. 

An `onVolumeScrubberChange` function is also added that sets the volume to the event target value when the input value changes and updates the volume in the state and an audio reference. The `onVolumeChange` function does not need to be used and the logic needs to be adjusted to ensure that the volume can be updated and that it mutes when the volume reaches 0.

**Think about:** Why do we have to add `audioRef.current.volume === 0` in addition to `audioRef.current.muted`?

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