@20i/use-roving-tabindex-a11y

Use Roving Tabindex A11y

This library provides a simple hook that enables keyboard navigation on any list, table body, or table header.

Usage

Usage Instructions:

• Create a roving tab index ref in your component

  const listRef = useRovingTabIndex()
  

• Place returned ref on any ul, tableBody, or tableHeader

  <ul ref={listRef}>...</ul>
  

• Give all focusable elements a tabindex of -1

  <button tabIndex={-1}>...</button>
  

• Give the one element you want to have the first default focus a tabindex of 0

  <ul ref={listRef}>
  <li><a tabIndex={0}>first link</a></li>
  ...
  </ul> )
  

Examples

Live examples!

Simple list

export const SimpleList: React.FC = () => {
  const listRef = useRovingTabIndex()
  return (
    <div>
      <h3>Simple List</h3>
      <ul ref={listRef}>
        <ListItem
          tabindex={0}
          title="Item 1"
          description="All the things you could ever want to know"
        />
        ...
      </ul>
    </div>
  )
}

Complex list with horizontal navigation

const ComplexListItem: React.FC<{
  title: string
  description: string
  tabindex?: 0 | -1
}> = ({ title, description, tabindex }) => {
  return (
    <li>
      {/* Initial focus */}
      <a href="#" tabIndex={tabindex ?? -1}>
        <h4>{title}</h4>
      </a>
      <p>{description}</p>
      {/* Focusable element with tabindex of 0 */}
      <button tabIndex={-1} onClick={() => console.log('subscribe')}>
        Subscribe
      </button>
    </li>
  )
}

Table

export const Table: React.FC = () => {
  const bodyRef = useRovingTabIndex()
  const headerRef = useRovingTabIndex()
  return (
    <table style={{ borderCollapse: 'collapse', borderSpacing: 0 }}>
      <thead ref={headerRef}>
        <tr>
          <Header tabIndex={0} name="Selected" />
          {/* This custom <Header /> tabIndex defaults to -1 */}
          <Header name="Name" />
          <Header name="Age" />
          <Header name="Favorite Color" />
          <Header name="Link" />
        </tr>
      </thead>
      <tbody ref={bodyRef}>
        <Row tabIndex={0} name="Janet" age={10} color="red" />
        {/* This custom <Row /> tabIndex defaults to -1 */}
        <Row name="Paul" age={15} color="green" />
        <Row name="Judy" age={18} color="blue" />
        <Row name="Peter" age={30} color="pink" />
      </tbody>
    </table>
  )
}

Other Helpful Utility

• useFocusOnFirstFocusable(): Auto focus on the first focusable element in an HTMLElement
• useFocusOnMount(): Auto focus on the HTMLElement that the returned ref is attached to

  ...
  const focusRef = useFocusOnMount()
  ...
  return <button ref={focusRef}>Focus on Me First!</button>
  

TODO's

• Invisible screen reader instructions are automatically added // Todo: Make optional flag?
• Make auto mode to find all focus-ables and handle setting their tabindex attribute

TSDX React w/ Storybook User Guide

Congrats! You just saved yourself hours of work by bootstrapping this project with TSDX. Let’s get you oriented with what’s here and how to use it.

This TSDX setup is meant for developing React component libraries (not apps!) that can be published to NPM. If you’re looking to build a React-based app, you should use create-react-app, razzle, nextjs, gatsby, or react-static.

If you’re new to TypeScript and React, checkout this handy cheatsheet

Commands

TSDX scaffolds your new library inside /src, and also sets up a Parcel-based playground for it inside /example.

The recommended workflow is to run TSDX in one terminal:

npm start # or yarn start

This builds to /dist and runs the project in watch mode so any edits you save inside src causes a rebuild to /dist.

Then run either Storybook or the example playground:

Storybook

Run inside another terminal:

yarn storybook

This loads the stories from ./stories.

NOTE: Stories should reference the components as if using the library, similar to the example playground. This means importing from the root project directory. This has been aliased in the tsconfig and the storybook webpack config as a helper.

Example

Then run the example inside another:

cd example
npm i # or yarn to install dependencies
npm start # or yarn start

The default example imports and live reloads whatever is in /dist, so if you are seeing an out of date component, make sure TSDX is running in watch mode like we recommend above. No symlinking required, we use Parcel's aliasing.

To do a one-off build, use npm run build or yarn build.

To run tests, use npm test or yarn test.

Configuration

Code quality is set up for you with prettier, husky, and lint-staged. Adjust the respective fields in package.json accordingly.

Jest

Jest tests are set up to run with npm test or yarn test.

Bundle analysis

Calculates the real cost of your library using size-limit with npm run size and visulize it with npm run analyze.

Setup Files

This is the folder structure we set up for you:

/example
  index.html
  index.tsx       # test your component here in a demo app
  package.json
  tsconfig.json
/src
  index.tsx       # EDIT THIS
/test
  blah.test.tsx   # EDIT THIS
/stories
  Thing.stories.tsx # EDIT THIS
/.storybook
  main.js
  preview.js
.gitignore
package.json
README.md         # EDIT THIS
tsconfig.json

React Testing Library

We do not set up react-testing-library for you yet, we welcome contributions and documentation on this.

Rollup

TSDX uses Rollup as a bundler and generates multiple rollup configs for various module formats and build settings. See Optimizations for details.

TypeScript

tsconfig.json is set up to interpret dom and esnext types, as well as react for jsx. Adjust according to your needs.

Continuous Integration

GitHub Actions

Two actions are added by default:

• main which installs deps w/ cache, lints, tests, and builds on all pushes against a Node and OS matrix
• size which comments cost comparison of your library on every pull request using size-limit

Optimizations

Please see the main tsdx optimizations docs. In particular, know that you can take advantage of development-only optimizations:

// ./types/index.d.ts
declare var __DEV__: boolean

// inside your code...
if (__DEV__) {
  console.log('foo')
}

You can also choose to install and use invariant and warning functions.

Module Formats

CJS, ESModules, and UMD module formats are supported.

The appropriate paths are configured in package.json and dist/index.js accordingly. Please report if any issues are found.

Deploying the Example Playground

The Playground is just a simple Parcel app, you can deploy it anywhere you would normally deploy that. Here are some guidelines for manually deploying with the Netlify CLI (npm i -g netlify-cli):

cd example # if not already in the example folder
npm run build # builds to dist
netlify deploy # deploy the dist folder

Alternatively, if you already have a git repo connected, you can set up continuous deployment with Netlify:

netlify init
# build command: yarn build && cd example && yarn && yarn build
# directory to deploy: example/dist
# pick yes for netlify.toml

Named Exports

Per Palmer Group guidelines, always use named exports. Code split inside your React app instead of your React library.

Including Styles

There are many ways to ship styles, including with CSS-in-JS. TSDX has no opinion on this, configure how you like.

For vanilla CSS, you can include it at the root directory and add it to the files section in your package.json, so that it can be imported separately by your users and run through their bundler's loader.

Publishing to NPM

We recommend using np.

Usage with Lerna

When creating a new package with TSDX within a project set up with Lerna, you might encounter a Cannot resolve dependency error when trying to run the example project. To fix that you will need to make changes to the package.json file inside the example directory.

The problem is that due to the nature of how dependencies are installed in Lerna projects, the aliases in the example project's package.json might not point to the right place, as those dependencies might have been installed in the root of your Lerna project.

Change the alias to point to where those packages are actually installed. This depends on the directory structure of your Lerna project, so the actual path might be different from the diff below.

   "alias": {
-    "react": "../node_modules/react",
-    "react-dom": "../node_modules/react-dom"
+    "react": "../../../node_modules/react",
+    "react-dom": "../../../node_modules/react-dom"
   },

An alternative to fixing this problem would be to remove aliases altogether and define the dependencies referenced as aliases as dev dependencies instead. However, that might cause other problems.