Learn Greensock, Safari and Xstream

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

screen-reader

Learn the basics of navigating through a web page using VoiceOver on MacOS in Safari.

Navigate a Webpage with VoiceOver in Safari

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

chrome-devtools

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

We can find issues with heading levels by utilizing our accessibility auditing tools.  The library react-axe, as well as the browser extension axe, will report any findings concerning heading levels.  The browser extension tota11y will annotate all heading levels on a page and show any in red that have issues.  Finally, we can check the Rotor in VoiceOver in Safari.  The Rotor should have a Headings menu and will list in order all of them that are found on the page.  If headings are missing or inappropriate this will help us find them as well.

Test for Heading Level Accessibility Issues

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

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

Add an Accessible Label to an Element from the Text of Other Elements

Labeling inputs, elements, and widgets add context and clarity for assistive technology such as screen readers. Beyond adding accessible labels to elements and widgets we can also provide additional descriptions.  Similar to how an `aria-labelledby` attribute works, an `aria-describedby` attribute can link the text from another element or elements to be used as a description for the given element.  

Some example use cases for using an `aria-describedby` are:
* providing instructions
* providing important usage details

Add Accessible Descriptions to Elements

When dynamic changes occur to content on a page they are usually visually apparent to users who can see the page but may not be made apparent to users of assistive technologies. ARIA live regions provide a way to make those dynamic content changes able to be announced by assistive technologies.

## ARIA attributes
* `aria-live`: the priority with which updates are read
* `aria-atomic`: whether the screen reader should always present the live region as a whole, even if only part of the region changes
* `aria-relevant` - takes a list of what type of changes should be announced

## Resources
* https://developer.mozilla.org/en-US/docs/Web/Accessibility/ARIA/ARIA_Live_Regions
* https://www.w3.org/WAI/PF/aria-1.1/states_and_properties#aria-live
* https://www.w3.org/WAI/PF/aria-1.1/states_and_properties#aria-atomic
* https://www.w3.org/WAI/PF/aria-1.1/states_and_properties#aria-relevant
* http://html.cita.illinois.edu/nav/form/aria/index.php?example=3

Define a Live Region to Ensure Dynamic Changes are Announced by Assistive Technologies

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

Did you know every Mac comes with a fantastic screen reader built-in? Learn the basics for operating Voiceover with Safari, including common key commands, the web rotor, and the help menu. We'll also set up keyboard tabbing in Safari and OSX's System Preferences, two requirements for accessibility testing that occasionally trip up users. In a future lesson, we'll compare Voiceover to Windows screen readers, since they work quite differently.

#### Resources
- Apple Voiceover commands and gestures: https://www.apple.com/voiceover/info/guide/_1131.html
- WebAIM Voiceover Tutorial: http://webaim.org/articles/voiceover/

Using the Voiceover screen reader to test for accessibility

Cycle.js is a framework where your app is described as a simple function taking an event stream as input and outputting an event stream.

cycle

This lesson is the first in an introduction to Cycle.js. We will see how to build from scratch a toy version of Cycle.js. See how to use RxJS to create simple web apps, and how to separate logic from effects.

Separate Logic from Effects in Cycle.js

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

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

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.

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