Learn Aria, Babel and Chrome

Optional chaining ?. in javascript is a new feature introduced in ES2020. Optional chaining changes the way properties are accessed from deeply nested objects. It fixes the problem of having to do multiple null checks when accessing long chain of object properties in javascript.

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

Optional Chaining

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

Chrome DevTools are incredibly useful for a frontend developer, sometimes we spend more time using them than our text editor of choice.

That's why it's so important to understand this tool better - those quick lessons will teach you things that will help you to become a more effective developer.

You will learn how to:

- **Use (experimental) CSS Overview to learn all about CSS used on a page in a minute**
- **Style console.log messages with CSS** - a _crucial_ skill for any senior developer (j/k)
- **Debug your code (on production and local environment) with logpoints**
- **Run a Lighthouse audit of your site**
- **Choose accessible colors for your website that have an AAA contrast ratio rating**
- **Force a DOM element state in Chrome DevTools**
- **Use Console utilities to make debugging easier**
- **Copy a network request as fetch or cURL with Chrome DevTools**

Have fun!

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

chrome-devtools

Chrome DevTools tips & tricks

In this course we’ll take a deep look at the Elements panel in the chrome devtools. We’ll step through each button and tab on this panel and discuss how to use them to interact with your web application as it runs.

Debug the DOM in Chrome with the Devtools Elements Panel

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 examines the Sources panel in the Chrome DevTools, which allows you to see what files are responsible for the various things on the screen. Bundled into this panel, though, is the single most useful tool for any JavaScript developer - the JavaScript Debugger. We’ll use the Debugger to inspect JavaScript as it runs, allowing you to watch (and even interact with) the state of your application as it runs in ways that’ll blow your mind if you’ve mostly used console.log to debug your applications to this point. 

Debug JavaScript in Chrome with DevTool Sources

This course will examine the Network panel in Chrome DevTools. We’ll step through the request log, examining the various properties exposed. We’ll talk about timing, filtering, throttling and generally using the network panel to better understand the ways in which our applications exist within a connected context.

Debug HTTP with Chrome DevTools Network Panel

This is a small collection of videos to help you get familiar with Chrome browser's performance oriented developer tools.
In this collection, learn how to record a performance profile, tweak the settings to get the most relevant profile and finally a look into the different sections of the performance data visualisation.

Basics of Chrome's Performance Devtools

Anything related to JavaScript performance

Javascript Performance

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

ASP.NET is an open source web framework for building modern web apps and services with .NET. ASP.NET creates websites based on HTML5, CSS, and JavaScript that are simple, fast, and can scale to millions of users.

asp-net

ASP.NET Core SignalR can push events from the server into your Client Application. In this video we will build a client side Todo app with Angular which consumes events from a ASP.NET Core SignalR backend to see how we can consume and synchronize data between our client side Angular Applications.

Consume ASP.NET Core SignalR values in an Angular Application

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

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/)

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