Learn Aria, Babel and D3

A large number of people are unable to use the web effectively due to an impairment or disability.

As developers there are several tools and techniques we can use to make our web applications accessible, ensuring a great user experience that includes everyone.

We all agree that Accessibility is important. However, it’s a broad landscape and can be overwhelming figuring out where to start!

Erin Doyle is an expert in creating accessible React applications and has developed a course that will give you a concrete process for testing, refactoring, and building your applications with accessibility in mind.

After this course, you'll have a jump start on auditing and fixing accessibility issues in your applications and gain a better understanding of your target users and how to approach your web app design from their perspectives.


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

Develop Accessible Web Apps with React

In this course we will learn and demonstrate the fundamental concepts and APIs of D3, on our way to building several common chart types. We’ll start with the building blocks upon which all D3 visualizations are built; things like scales, interpolators, and selections. We’ll see how to load data with D3, and how to put its full name, Data Driven Documents, into action. We’ll build column and bar charts, scatter plots, and area charts. Most importantly, we’ll gain an understanding of the conventions and patterns that underlie all D3 projects and examples, enabling you to dissect, understand, and build virtually any D3 visualization on the internet.

D3.js is a JavaScript library for manipulating documents based on data. D3 helps you bring data to life using HTML, SVG and CSS. D3’s emphasis on web standards gives you the full capabilities of modern browsers without tying yourself to a proprietary framework, combining powerful visualization components and a data-driven approach to DOM manipulation.

Build Interactive JavaScript Charts with D3 v4

Accessibility (or a11y) is an important but often neglected in the world of web development. Many developers find themselves coding user interfaces without any knowledge of keyboard or screen reader requirements. 

The fact is that accessibility doesn't happen by accident. Often it is seen as too hard or time consuming. This doesn't have to be the case. By following a handful of high-value patterns and practices, we can open our web apps to humans that otherwise wouldn't be able to interact with them at all.

This course will introduce you to accessibility through hands-on, technical examples that are way more effective than reading 10-year-old static web content.



WAI-ARIA, the Accessible Rich Internet Applications Suite, defines a way to make Web content and Web applications more accessible to people with disabilities. It especially helps with dynamic content and advanced user interface controls developed with Ajax, HTML, JavaScript, and related technologies. 

aria

Start Building Accessible Web Applications Today

This course covers D3 v3. If you'd like to learn about v4 of D3 (the latest version) [click here for the course on that](https://egghead.io/courses/build-interactive-javascript-charts-with-d3-v4).

This series will gently guide you through the first steps in getting to know D3. The curve can be steep, but with a few simple tools, you'll be charting your buns off in no time flat.

Use D3 (v3) to Build Interactive Charts with JavaScript

Skeleton screens show users that content is loading, offering a vague preview of how content will look once it fully loads.

CSS Animations are crucial for the perceived performance purposes since it shows for the user the content is loading by using animations as feedback for whoever is accessing the page. 

Follow the steps in this course and you will learn how to create a beautiful and pleasant Skeleton Loader for your web app using CSS animations, focusing on Web Accessibility and Web Semantic.

Creating Accessible Skeleton Loader Animation from Scratch with HTML and CSS

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

Converting all of our modern JavaScript into ES5 compatible syntax is a great way to use modern features while targeting older browsers. What happens when the browsers natively support these language features? Then it no longer makes sense to transform that code or to include polyfills that will go unused. In this lesson, we’ll add the `@babel/polyfill` package and configure `babel-preset-env`

Target specific browsers with babel-preset-env and the babel pollyfill

The Chrome Developer Tools (DevTools for short), are a set of web authoring and debugging tools built into Google Chrome.

chrome-devtools

What's in a name? In this lesson, I'll explain the concept of naming interactive elements for screen reader users, including forms, buttons, and links. You'll learn how to debug accessible names and descriptions using the Chrome Accessibility Developer Tools (previously a Canary experiment, now in Chrome), using multiple labeling techniques. We'll also listen to the effects of proper accessible names and descriptions in Voiceover and Safari.

For more information and the nitty-gritty browser implementation algorithm, refer to WAI-ARIA 1.1: 
- https://www.w3.org/TR/wai-aria-1.1/#namecalculation
- https://www.w3.org/TR/accname-1.1/

What is Accessible Name Calculation?

In this lesson, we are going to use aria-current to give a screen reader user more context about what the current page is. Historically, many developers use an `.active` class to indicate that the page in a menu is the same that you're on. 

Instead of using a class, we are going to use the aria-current attribute to add more semantic value to the HTML and use that attribute to style the active link.

Note: VoiceOver testing works best on the Native Safari Browser, hence why we should always use Safari to test.

More resources:
- [Using the aria current attribute](https://tink.uk/using-the-aria-current-attribute/)
- [W3 WAI-ARIA - aria-current](https://www.w3.org/TR/wai-aria-1.1/#aria-current)
- [Breadcrumb Example - w3-WAI ARIA Practices](https://www.w3.org/TR/wai-aria-practices-1.1/examples/breadcrumb/index.html)

Add Semantic Styling to the Current Page of a Navigation Item with aria-current

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

In this lesson, we will be going over the attribute `aria-expanded`. Instead of using a class like `.open` we are going to use the `aria-expanded` attribute to style.

This accomplished double duty because we have semantic value and visual indicators that a button is open and closed.

To test this, I opened up Safari and used CMD + F5 to turn VoiceOver on. 

- [An Introduction to ARIA States](https://www.a11ywithlindsey.com/blog/introduction-aria-states)
- [w3c Using aria-expanded to indicate the state of a collapsible element](https://www.w3.org/WAI/GL/wiki/Using_aria-expanded_to_indicate_the_state_of_a_collapsible_element)

Add aria-expanded to add semantic value and styling

Continuing to add to our accessibility auditing toolset: react-axe goes hand in hand with eslint and specifically the eslint-plugin-jsx-a11y plugin.  While eslint analyzes our static code, react-axe is able to audit the elements that are available in the DOM at runtime.  As components get rendered into the DOM by React, react-axe is able to immediately check them for potential accessibility issues and will output any findings to the console.  Adding this tool to our workflow gives us accessibility checking as we're developing so that we can eliminate a plethora of potential issues as early as possible.

## Resources
* [List of all rules supported by react-axe](https://github.com/dequelabs/axe-core/blob/develop/doc/rule-descriptions.md)
* [Documentation of the Configuration Object](https://github.com/dequelabs/axe-core/blob/master/doc/API.md#api-name-axeconfigure)
* [How Deque Labs makes decisions on axe rules](https://github.com/dequelabs/axe-core/blob/develop/doc/accessibility-supported.md)

Use react-axe to Audit Accessibility Issues at Runtime during Development

The axe browser extension (for Chrome and Firefox) is an immensely helpful tool for auditing web pages for accessibility defects.  This extension is powered by the same rules engine developed by Deque Labs in their axe-core open source library which also powers the react-axe development tool.  Each reported defect offers a ton of information about the defect, why it's a problem, severity level, groups impacted and ways to fix the defect.  This can be a great resource for learning more about how to write accessible code.

## Resources
* [Chrome browser extension](https://chrome.google.com/webstore/detail/axe-web-accessibility-tes/lhdoppojpmngadmnindnejefpokejbdd)
* [Firefox browser extension](https://addons.mozilla.org/en-US/firefox/addon/axe-devtools/)

Use the axe Browser Extension to Audit a Web Page for Accessibility Issues

Here we use HTML and CSS to create a stylish yet semantic tooltip on a form input. I am using `aria-describedby` to create a relationship with the input and the tooltip. Then I use CSS to style the tooltip and control when it appears or disappears both on hover and focus.

In this video, we use VoiceOver. To test that on a MacOS, use CMD + F5.

A few resources:
- [CSS Triangle](https://css-tricks.com/snippets/css/css-triangle/)
- [a11y Style Guide - Tooltips](https://a11y-style-guide.com/style-guide/section-forms.html#kssref-forms-tooltips) - I used this to gut check and with some help with those transitions. 
- [Using VoiceOver to Evaluate Web Accessibility](https://webaim.org/articles/voiceover/)

Create an Accessible Tooltip on a Text Input

Landmark regions are used by screen readers to make it easier for users to navigate the content on the page by defining the structure of the page.  Tools like the Rotor in VoiceOver rely on landmark regions to provide users with the ability to skip directly to the desired section of the page.  We can do this either using HTML5 landmark elements or `<div>` elements with aria roles. In the past, the recommendation was to use both but now we should only use one or the other.

The following are ARIA roles for landmark regions:
* `banner`
* `complementary`
* `contentinfo`
* `form`
* `main`
* `navigation`
* `search`
* `application`

## References
* https://dequeuniversity.com/assets/html/jquery-summit/html5/slides/landmarks.html
* https://www.w3.org/WAI/GL/wiki/Using_ARIA_landmarks_to_identify_regions_of_a_page
* https://www.w3.org/TR/html-aria/#docconformance

Define Landmark Regions of a web page using ARIA roles

tota11y is a great tool to add to your accessibility auditing toolkit.  tota11y is a browser extension available for Chrome and Firefox that helps visualize accessibility violations (and successes), while educating on best practices.  It can make for a really helpful supplement to other accessibility auditing tools.

## Resources
* [About tota11y](https://khan.github.io/tota11y/)
* [Chrome browser extension](https://chrome.google.com/webstore/detail/tota11y-plugin-from-khan/oedofneiplgibimfkccchnimiadcmhpe?hl=en)
* [Firefox browser extension](https://addons.mozilla.org/en-US/firefox/addon/tota11y-accessibility-toolkit/)

Use tota11y to Visualize Accessibility Issues

It's very important to experience our web applications using the tools and techniques that our users are using.  Many of our users out there may have vision impairments and may use tools or adjust settings to help them see better. Learn how to change the accessibility display preferences on Mac to test your application for issues that may arise due to a lack of contrast between foreground and background colors in your web application which can be exacerbated when users have to adjust these display preferences.

## Resources
* [MacOS Display Preferences User Guide] (https://support.apple.com/guide/mac-help/change-accessibility-display-preferences-unac089/mac)

Change Display Preferences on Mac to Find Color Contrast Accessibility Issues

Using our accessibility auditing toolkit we can find issues concerning landmark regions in our web application.  The react-axe library will report findings in the JavaScript console of the browser.  We could also run the axe browser extension to see the same results.  The tota11y browser extension will annotate any landmark regions on the page and therefore if none are annotated it may indicate that they aren't any (_NOTE: tota11y will only annotate landmark regions using aria roles and not those using HTML5 elements_).  Finally using the VoiceOver Rotor in Safari will show us whatever landmark regions have been defined in the Landmarks menu. 

Test for Landmark Region Accessibility Issues in React

Landmark regions are used by screen readers to make it easier for users to navigate the content on the page by defining the structure of the page. Tools like the Rotor in VoiceOver rely on landmark regions to provide users with the ability to skip directly to the desired section of the page. We can do this either using HTML5 landmark elements or <div> elements with aria roles. In the past, the recommendation was to use both but now we should only use one or the other.  We should prefer HTML5 to ARIA roles when possible.

The following are HTML5 elements for landmark regions:
* article
* aside
* header
* footer
* main
* nav
* section

## References
* https://dequeuniversity.com/assets/html/jquery-summit/html5/slides/landmarks.html
* https://www.a11ymatters.com/article/intro-html5-sectioning-elements/
* https://www.w3.org/TR/html-aria/#docconformance

Define Landmark Regions of a web page using HTML5 sectioning elements

Labeling inputs, elements, and widgets add context and clarity for assistive technology such as screen readers. Some elements do not already have some sort of labeling text being displayed visually, such as a `<button>` without descriptive text or an `<icon>` or part of a more complex widget.  Others may have some form of text label but it is not descriptive enough for those who cannot see it.  The addition of an `aria-label` attribute to the element will provide it with an accessible label so that when that element is focused by a screen reader, for instance, a label is read that better describes the element and what a user can expect from it.

Add Accessible Labels to Elements Whose Labels are Not Clear Enough

Labeling inputs, elements, and widgets add context and clarity for assistive technology such as screen readers. Some elements do not already have some sort of labeling text being displayed visually, such as a `<button>` without descriptive text or an `<icon>` or part of a more complex widget.  Others may have some form of text label but it does not provide enough context to be useful enough for those that cannot see it.  The addition of an `aria-label` attribute to the element will provide it with an accessible label so that when that element is focused by a screen reader, for instance, a label is read provides better context for the element and what a user can expect from it.

Add Accessible Labels to Provide Elements with More Context

Labeling inputs, elements, and widgets add context and clarity for assistive technology such as screen readers.  When there are already one or more other elements that themselves can be used to provide labeling text to another element an `aria-labelledby` attribute can be added to that element.  

Some examples of appropriate use cases for using an `aria-labelledby` are:
* Combine multiple labels together
* Associate headings with regions
* Label for a widget

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