Learn Firefox, Greensock and Radium

Animations attract the eye and add a higher level of engagement for your users. But they’re not easy to set up, and they don’t always look the way they should on every browser. 

Greensock is the best platform available for creating performant, highly-customizable animations. This course will walk you through the features of Greensock, including how to:

- animate an element
- manually control an animation
- animate between CSS classes

…and more, with cross-browser support to ensure your animations look sharp everywhere.

Ultra high-performance, professional-grade HTML5 animation for the modern web

greensock

Create Amazing Animations with GreenSock

GreenSock supports all of the CSS3 3d properties, so you can freely rotate around X, Y, and Z axises with rotationX, rotationY, and rotationZ. Once that's set up, you can tweak the perspective of the element with transformPerspective.

Spin Elements in 3d with GreenSock

By default, elements use their own perspective, so if you rotate multiple elements on the page the perspective will seem a bit off for each of them. The solution is to set the perspective on the container element, then each child element will follow the parents' perspective.

Control the Shared 3d Perspective of Multiple Elements with GreenSock

Sometimes you want to leave an animation looping without any user interaction. This is done using the "repeat" and "yoyo" properties combined to keep the tween moving back and forth from the start properties to the end properties.

Loop a Tween Forever Using Yoyo and Repeat with GreenSock

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

chrome-devtools

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

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

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

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

The `gsap.set()` tween (or animation container) is a zero-duration tween that instantly applies a property to an HTML element. In addition, there is a subtle but important difference between `opacity` and Greensock's `autoAlpha` properties. You will learn how to hide a menu on page load and also how to prevent the element from flashing on page load. This lesson contains Greensock's basic building blocks that are used to create advanced animations with UI elements.

To add the latest Greensock library to your project, go to [Greensock's website](https://greensock.com/). Fun fact: GSAP stands for Greensock Animation Platform, and their current latest version is GSAP 3!

A common programming convention for Greensock I like to follow is, if you're going to animate a property with Greensock, keep it in Greensock, otherwise, if you are not going to animate a property, keep it in your CSS.

Hide a Menu with GSAP3's set() Tween and autoAlpha Property

Cascading Style Sheets bring order and beauty to our applications.

Firefox DevTools has an awesome feature that helps you determine Inactive CSS, to know why it's inactive, it gives you hints on how to fix it, and even links to documentation for additional help.

Understand why CSS has no effect with the Inactive CSS rules indicator in Firefox DevTools

CSS Media queries are heavily used across web pages for different reasons, such as make your web pages responsive, but what if we can use them to improve web accessibility as well?

In this video, I’m sharing How to use CSS Media Queries for web accessibility in your web app, combining the user preferences choice with `prefers-color-scheme` media query and enabling dark mode in your web app.

Create a Dark Mode Theme in Your Web App Using CSS Media Query

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

In a CSS library like Bootstrap we can set a button's style to be "primary" or "secondary" by appending classes. For React components we want to be able to do this via props. Radium enables this by composing styles via an array. This mimicks the cascade of CSS.  

Radium: Updating Button Styles via Props

React's inline styles allow components to stand on their own by not requiring any external CSS. However HTML's style attributes don't support pseudo selectors like `:hover` and `:active`. By using Radium to listen to mouse events we can restore `:hover` and `:active` selectors to inline styles.

Styling a React button component with Radium

The React Developer Tools are an extension that can be added to Chrome and Firefox to help with debugging React applications. In this lesson, we walk through how to use these developer tools to view, edit, and debug your React components, including: the `React` browser tab, inspecting components in parallel with the `Elements` tab, using React components in the console, searching by component name, and debugging component state and props.

Debugging components with the React Developer Tools extension

In this lesson, we will look at Greensock's Draggable API. We will implement a scrollable `<div>` container and explore some options available.

Create scrollable DOM elements with Greensock

Animations can make people sick, or worse! By adding animation toggles and listening in to the user's system preference for reducing motion on OSX and iOS, we can give them more control over our interfaces. Animation can be a safety issue; let's do something about it!

Warning: there is a flashing animation in the video.

In this lesson:
- [prefers-reduced-motion](https://webkit.org/blog/7551/responsive-design-for-motion/)

WCAG 2.1, Guideline 2.3: Seizure risks
- https://www.w3.org/WAI/WCAG21/quickref/?versions=2.0#qr-seizure-does-not-violate

Your Interactive Makes Me Sick
- https://source.opennews.org/articles/motion-sick/

Accessible animations with reduced motion

Modern development requires modern tooling. Rather than adding GreenSock as a script to an HTML page, we're going to install GreenSock using Yarn and set up our development environment using Parcel. This will allow us to quickly iterate and test out our animation ideas. GreenSock is abbreviated as `gsap` when importing.

Setup GreenSock as a Module with Parcel

Animating an element to a click event is as simple as passing the x and y coordinates of the click event to the properties of the `TweenMax.to` call. To be able to center the element where the mouse clicks, you also need to adjust the special xPercent and yPercent properties so the element is properly offset.

Animate and Center an Element to a Click Event with GreenSock

Rotating an element with GreenSock is as simple as changing the `rotation` property using `TweenMax`. But there's also a hugely convenient trick using the `+=` or `-+` syntax as a string that allows you to adjust based on the previous value of the rotation.

Rotate an Element Based on Previous Values with GreenSock

Animations often have multiple steps. GreenSock makes this simple with the concept of a timeline where you code each point you want your element to move to. This lesson will show you how to set up a timeline as well as pause and resume the timeline animation.

Create Animation Steps with GreenSock's Timeline

You often need to pause or resume an animation based on whether or not the current animation running. The `isActive()` getter returns a boolean that provides you with that information (the opposite information can be found with using the `paused()` getter).

Pause or Resume an Animation by Checking isActive with GreenSock

GreenSock also supports the ability to animate `from` a variable point to the current point. If you think `to` starts at a static point and moves to a variable point then `from` essentially does the opposite. `fromTo` supports the scenario where both points are variables and requires passing in a "from" set of properties and a "to" set of properties.

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