Learn Eslint, Openapi and Tachyons

In this course, we will build a ToDo API that stores notes using the OpenAPI Specification (Swagger). We will start with a blank API definition using the Swagger Online Editor. The Swagger definition file will be used to create a Node.js API. Along the way, we will discover how to implement additional details required for a fully functional API requests and responses. We will also learn about the powerful capabilities of Swagger to generate server side code and client libraries.

Open API Initiative (OAI) is focused on creating, evolving and promoting a vendor neutral API Description Format based on the Swagger Specification

openapi

Build Node.js APIs with OpenAPI Spec (Swagger)

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

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

The pluggable linting utility for JavaScript and JSX.

eslint

We have a number of options to use when testing for accessibility issues concerning alternative text for images.  The react-axe library and axe browser extension will both report when an image is missing alternative text.  The tota11y browser extension will annotate any images that are missing alternative text.  Running eslint with the eslint-plugin-jsx-a11y plugin installed will report on any `<img>` elements missing an `alt` attribute.  Finally, we can use a screen reader to actually hear what is read when an image has focus.

Test for Image Alternative Text Accessibility Issues

Images must have text alternatives that describe the information or function 
represented by them so they can be read and understood by those using screen readers.

## Alternative text for images
* All `<img>` elements should have an `alt` attribute provided
    * When not provided many screen readers will fallback to reading the file name instead
* The `alt` value should not include words like _“image”_, _“picture”_ or _“icon”_
    * Screen readers are already announcing that the element is an image
* Images that are decorative only and provide no information or function to the page should be hidden from Assistive Technologies by providing an empty `alt` attribute (`alt=””`)

## References
* https://www.w3.org/WAI/tutorials/images/
* https://www.w3.org/WAI/tutorials/images/decision-tree/
* https://www.w3.org/WAI/tutorials/images/tips/
* https://www.w3.org/WAI/tutorials/images/informative/
* https://www.w3.org/WAI/tutorials/images/functional/
* https://www.w3.org/WAI/tutorials/images/textual/

Define Images with Appropriate Text Alternatives

Our accessibility auditing toolkit makes it very easy for us to test for any form controls that are missing labels or are not correctly associated with their labels.  Running Eslint with the eslint-plugin-jsx-a11y installed will show us any form controls with missing or unassociated labels.  Running react-axe or using axe to audit a web page will similarly list any of these findings.  Finally using tota11y we can annotate any form controls on a page that are missing labels.  This is definitely some of the lower hanging fruit that we can easily find and fix when making our applications accessible!

Test for Form Control Label Accessibility Issues

Labeling inputs, elements, and widgets add context and clarity for assistive technology such as screen readers.  Elements of a `<form>` such as `<input>` or `<textarea>` or `<select>` should be labelled by using a `<label>` element.  Placeholder text can be used in addition to a label but should not be used in place of a label as not all assistive technologies respect placeholder text.

Ensure Form Controls have Accessible Labels

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

In this lesson you will learn how to use the eslint yeoman generator to scaffold a new plugin to provide custom rules for your project. 
You will also be able to check the basic skeleton for an eslint ruleand a working example rule to apply a naming convention for async functions.

Scaffold an eslint Plugin with Yeoman

Nx already comes with a default TypeScript setup. Although you can opt-out of that and generate plain JS based components, especially in a large setup TypeScript can be beneficial in uncovering potential issues early. To add an extra level, Nx also comes with preconfigured eslint for all the apps and libraries. In this lesson we're going to explore the lint setup and how it can be used.

Linting a React app with Nx

Swagger is a project used to describe restful APIs using the OpenAPI Specification. It allows you to document your API so consumers understand the endpoints, parameters, and responses. In this lesson, I'll show you how to install the swagger command line tool, create a new API project using swagger, and introduce you to the swagger API editor.

Create an API with Swagger

In this lesson, you will learn how to define an HTTP GET endpoint using Swagger with URL parameters to identify the ID of the Todo item being requested.

Define an HTTP GET Endpoint with URL Parameters for a Node.js Server with Swagger

Schema definitions allow you to define the format and types of data sent and received by your API. This allows consumers of your API to be confident in using your API. In this lesson, you will learn how to create a schema definition for the Todo API server. 

Create An API Schema Definition Using Swagger

In this lesson, you will learn how to create an HTTP GET endpoint for a node.js server using Swagger. This endpoint will be used to return all of the Todo items from Elasticsearch to the client.

Define an HTTP GET Endpoint for a Node.js API Server with Swagger

This lesson shows you how to delete a Todo item from Elasticsearch using the Todo ID from the URL parameters according to the specifications defined in your Swagger API docs.

Create a Node.js function for an HTTP DELETE request for a Swagger API

This lesson demonstrates how to access the ID of a Todo item being deleted from the URL parameters when used with an HTTP DELETE method.



Define an HTTP DELETE Endpoint for a Node.js API Server with Swagger

In this lesson, you will learn how to define HTTP POST operations for your Todo API server using Swagger. Creating the endpoint, passing the todo in the request body, and parsing the todo are all demonstrated.

Define an HTTP POST Endpoint for a Node.js Server with Swagger

This lesson will teach you how to create the javascript functions defined by the Swagger specification to return all Todo items to the client when requested with an HTTP GET method.

Create a Node.js function for an HTTP GET request for a Swagger API

In this lesson, you will learn how to define multiple parameters in the API specification to identify the ID of the Todo item being updated in the URL, as well as the contents for the updated Todo item in the body of the request.

Define an HTTP PUT Endpoint for a Node.js API Server with Swagger

APIs created with Swagger have a built-in mock function, allowing you to mock responses from your API prior to writing the backend code to make it functional. In addition to learning how to enable this feature, I will show you how to write your own functions to enhance the mock responses returned when using the Swagger mock feature.

Mock API Responses with Swagger

There are a lot of great monitoring tools available for Node.js. It is also incredibly easy to build monitoring into your application. In this lesson, we will add precision monitoring to the function calls in the Todo API server, log it to the console, and persist those results to Elasticsearch where they can later be reviewed, graphed, and analyzed.

Build Monitoring into your API Server

This lesson shows you how to create the functions defined in the Todo API specification to create new Todo items when received in HTTP POST methods. You will also see the errors you will get when CORS is not properly configured and how to resolve them by installing the NPM CORS package.

Create a Node.js function for an HTTP POST request for a Swagger API

This lesson will teach you how to update a Todo item in Elasticsearch when received from an HTTP PUT method in your API server built with Swagger.

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