Learn Canvas, Jest and Screen-reader

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 collection, we build a minimal flashcard application using React, primarily focusing on function components and the hooks API. To make sure we can understand and maintain existing code, there are also a few lessons toward the end that use class components so you can get familiar with the syntax. We cover important React concepts, and sprinkle in libraries that are pretty standard in the ecosystem like @reach/router, Jest, and React testing library. We start with create-react-app so we can get right into it without worrying about configuring tooling. There's [a separate course for that here](https://egghead.io/courses/modern-javascript-tooling-with-react?af=5mx0ie)

jest

Build a React App with the Hooks API

In this course we are going to work through properly setting up Enzyme with Jest to test rendered components. This includes the nitty gritty of making our testing environment work with various versions of React. After we get our environment setup ready, we’ll work through the different ways we can render a component within our test pages. With a rendered component we can now test component methods and properties to assert that they are what is intended. 

Test React Components with Enzyme and Jest

Best practices for building & testing redux applications have changed dramatically over time. This course aims to be a comprehensive and up-to-date resource for those seeking to confidently test their redux apps. Whether you're just getting started or want to improve on your existing testing strategy, there will be something in this course for you.

This first few lessons of this course look at how to add jest to an existing react/redux application that was built on top of [vite](https://vitejs.dev/). We cover basic functionality like using `npm test` vs `npx jest` and generating and using [code coverage](https://jestjs.io/docs/cli#--coverageboolean) to inform our testing strategy.

The next 10 or so lessons cover the specifics of unit testing the redux code in our application. We'll go over how to test reducers, selectors and thunks. As part of this we'll touch on mocking APIs and using [Redux Mock Store](https://github.com/reduxjs/redux-mock-store) as well as running actions through our applications' actual reducers to broaden our test coverage.

In the final part of this course we'll look at how we can test our redux connected react components using the various utilities that come with the [React Testing Library](https://testing-library.com/docs/react-testing-library/intro/). We'll cover simulating various kinds of user input with the [User Event Module](https://testing-library.com/docs/ecosystem-user-event), populating our redux store with test data, using [jest spies](https://jestjs.io/docs/jest-object#jestspyonobject-methodname), how to wait for asynchronous tasks to complete, and several approaches for finding & asserting that visual elements exist on the page.

This course is built on top of content that was created for the [Modern Redux with RTK and TypeScript](https://app.egghead.io/playlists/modern-redux-with-redux-toolkit-rtk-and-typescript-64f243c8) course and I highly recommend you start there if you haven't completed it already. It does expect a *basic* familiarity with react, redux and jest. TypeScript is used in these lessons, but is not a major focus and hopefully won't distract you too much if you prefer plain JavaScript.

No matter your experience level with redux and testing react applications, I'm confident your abilities will level up as you watch this course and follow along with the examples.

Thank you!

Confidently Testing Redux Applications with Jest & TypeScript

A <canvas> element provides scripts with a resolution-dependent bitmap canvas, which can be used for rendering graphs, game graphics, or other visual images on the fly.

canvas

Learn some of the different ways you can affect the graphical content that you are drawing to a canvas. We'll cover global alpha, global composite operations and shadows.

Canvas Effects

With the HTML `canvas` you can easily draw text as well as graphics. Let's take a look at basic text manipulation on the canvas.

Drawing Text on Canvas

In this lesson, we cover several different ways to animate graphics drawn to Canvas.

Animating with Canvas

When drawing on the HTML5 canvas element, your fills aren't limited to flat colors. You can use gradients to get smoothly blended color fills on your drawn elements.

Gradient Fills on the HTML5 Canvas

screen-reader

There are many techniques for hiding content in user interfaces, and not all are created equal! Learn how different hiding techniques in HTML, CSS and ARIA impact keyboard and screen reader users in addition to visual display. As a bonus, we'll also take a look using a screen reader on a mobile device.

How Visible vs. Hidden Elements Affect Keyboard/Screen Reader Users

Transformations can change the default canvas coordinate system and create complex drawings with much less code.

Canvas Transformations

In this lesson, listening for and handling mouse and keyboard events in Canvas is covered.

Listening for Mouse and Keyboard Events with HTML Canvas

The HTML Canvas element allows us to access powerful drawing APIs from JavaScript. In this lesson, the first in a series, we will learn about `<canvas>`, and get ready to start drawing.

Introduction to the HTML Canvas element

Now that we have an HTML5 canvas to draw on, let's take a look at drawing simple lines and rectangles with JavaScript

Drawing Paths - Lines and Rectangles

When drawing on your HTML canvas in JavaScript, you aren't restricted to straight lines. Using curves and arcs you are able to create smooth curved lines.

Drawing Paths - Curves and Arcs

You aren't limited to boring black lines when drawing on the HTML5 canvas element. Using styles, you can program interesting colorful images with JavaScript.

Drawing Styles on HTML5 Canvas

In this lesson, you'll learn how to read and write individual pixel color values from a canvas.

Canvas and Pixels

In addition to vector drawing, you can draw bitmap images into a canvas, and also retrieve a bitmap based on the content in a canvas.

HTML Canvas and Images

Jest is a painless JavaScript unit testing framework from Facebook. It is designed to be super easy to setup and is packed full of powerful features. In this lesson we see how easy it is to add to your TypeScript project. This will be followed by a quick example application.

Getting started with Jest using TypeScript

React Storybook allows for easy snapshot testing integration with Facebook's Jest testing framework. Snapshot testing allows you to capture the state of your UI and then notify you when that UI has been altered. We can easily create and update snapshots with Storybook!
 




Jest Snapshot Testing with React Storybook

The reducer is at the center of how Redux manages state. In this lesson we’ll create a reducer function and see how Redux takes in state and actions and returns updated state. We’ll write and run unit tests using Jest to verify that our reducer function is working as expected.

Create a Redux-Style Reducer Function

In this lesson, I use Enzyme and Jest's Snapshot functionality to write an integration test for a component called CounterConsumer that consumes the Render Prop component Counter. This integration test is great because it doesn't necessarily care that CounterConsumer uses Counter behind the scenes, just that it works when integrated.

Other resources:
[Testing ⚛️ components using render props](https://blog.kentcdodds.com/testing-%EF%B8%8F-components-using-render-props-5623ab1814c)


Search

Search Results