react-a11y-alt

React A11y

Warns about potential accessibility issues with your React elements.

This is a fork of reactjs/react-a11y, that didn't seem to get the love it deserves.

The original repo had a lot of open issues and unmerged pull requests. Eventually, I would like to see all code merged back into the original!

To see what's changed, look at Differences from react-a11y.

API on this fork

On this fork, the API moves away from the API in the upstream reactjs/react-a11y. Although the API will be different, transitioning between API's is made as smooth as possible because of the deprecation warnings and building the new defaults on top of the old API.

Installation

Run:

npm install romeovs/react-a11y

I want to prevent creating a new npm package for the fork, to reduce confusion and ease possible merging of the forks. However, if there is enough interest, I will probably do it anyway.

Usage

In your main application file, require the module and call it, you'll start getting warnings in the console as your app renders. Note that by default all rules are turned off s oyou need to turn them on first (by setting them to "warn" or "error").

import React    from 'react'
import ReactDOM from 'react-dom'
 
if (ENV === 'development') {
  const a11y = require('react-a11y').default
  a11y(React, ReactDOM, {
    rules: {
      'img-uses-alt': 'warn'
    , 'redundant-alt': [ 'warn', [ 'image', 'photo', 'foto', 'bild' ]]
    // ...
    }
  })
}

You probably don't want to call it if you're in production, since it patches the React rendering functions and this might make this slower.

Options

These are the supported configuration options, annotated using flow type annotations

a11y(React : React, ReactDOM : ReactDOM, opts : object? )

React is the React object you want to shim to allow the accessibility tests.

ReactDOM is the ReactDOM object you're using to render the React components. This is only used on the client side, so you can safely omit it when using react-a11y in node.

options:

• plugins : [string] An array of strings corresponding to names of plugins to be used. Eg. if the array contains 'aria-wai' it would include the rules in a (yet to be written) react-a11y-plugin-aria-wai module. You are responsible for installing this module.

• rules : object The configuration options for each of the rules. This uses the same format as eslint does:

  const rules = {
    'img-uses-alt': 'off'
  , 'redundant-alt': [
      'warn'
      // other options to pass to the rule:
    , [
        'foto'
      ]
    ]
  }
   

  Refer to the rule docs to see what options are defined for each rule.

• reporter : object => undefined Use this to modify how the warnings are displayed. The reporter is a function that accepts an object with the following keys:

  • msg : string - the error message
  • tagName : string - the tagName of the violating element (eg. 'img')
  • severity : string - the severity as configured by the user in the corresponding rule configuration (one of 'off', 'warn', or 'error')
  • props : object - the props as passed to the element
  • displayName : string? - the displayName of the owner, if any
  • DOMNode : object? - the violating DOMNode as rendered to the browser DOM, this is only available on when react-a11y is running in the browser.
  • url : string? - The url to a webpage explaining why this rule is important The default reporter displays all the information it can, but listens to the deprecated options includeSrcNode, warningPrefix and throwErro andthrowError`.

• filterFn : (string, string, string) => boolean You can filter failures by passing a function to the filterFn option. The filter function will receive three arguments: the name of the Component instance or ReactElement, the id of the violating element, and the failure message.

  Note: If it is a ReactElement, the name will be the node type (eg. div)

  // only show errors on CommentList
  const commentListFailures = function (name, id, msg) {
    return name === "CommentList";
  }
   
  a11y(React, ReactDOM, { filterFn: commentListFailures });

Cleaning Up In Tests

Use the restoreAll() method to clean up mutations made to React. Useful if you are using react-a11y in your test suite:

beforeEach(() => a11y(React))
afterEach(() => a11y.restoreAll())

Writing plugins

The rules in this version of react-a11y are pluggable! You can write your own plugin to add more rules. Have a look at writing plugins in the docs to get started!

Differences from upstream react-a11y

I will try to stay close to the upstream react-a11y API, and document differences here.

• The API is totally different. It has a simple plugin system so other poeple can write and publish their own rules. The options have become much simpler also.
• Started using ReactDOM.finDOMNode instead of document.getElementById, as noted in upstream #54. This fixes a lot of issues from upstream:
  • #54 Use React.findDOMNode to log element references
  • #55 Consider using ref to log element references when there is a warning
  • #77 Breaks pure-render checks
  • #85 Different react-a11y ids (server side render)
• Fixed upstream issue #102 by correctly inferring the component instance.
• Removed depency on object.assign
• Added some more rules (and will continue to do so), based on the great work in eslint-plugin-jsx-a11y and on the Google Chrome Audit rules.
• Write a lot more tests.
• Tests now work both browser-side as client-side with the exception of tests that rely on the specific environment.

TO DO

These are things I need to do in the short run to make the project usable:

• add a build-step that mirrors changes in code-style such as increased use of ES6 features.
• add eslint config so poeple can collaborate more easy.
• put up a travis worker to make merging easier.
• write docs about how to write plugins.
• normalize props before passing to the rules, eg. change aria-hidden into ariaHidden, so every test can use the same method. This makes no sense since React only renders aria-hidden.
• implement all the rules that are in facebook/react-a11y and in eslint-plugin-jsx-a11y.
  • img-uses-alt (MISSING_ALT)
  • label-uses-for
  • mouse-events-map-to-key-events
  • no-access-key
  • no-hash-ref
  • onclick-uses-role (NO_ROLE)
  • onclick-uses-tabindex (NO_TABINDEX)
  • redundant-alt
  • use-onblur-not-onchange
  • valid-aria-role
  • button-role-space (BUTTON_ROLE_SPACE)
  • button-role-enter (BUTTON_ROLE_ENTER)
  • hidden-uses-tabindex (TABINDEX_REQUIRED_WHEN_ARIA_HIDDEN)
  • hash-href-needs-button
  • tabindex-needs-button
  • use-label (NO_LABEL)
  • no-unsupported-element-uses-aria
  • avoid-positive-tabindex
• make rule testing machinery available to plugins.
• allow rule tests to return promises, so they can be asynchronous.
• think of a way to lose the setTimeout when testing for absence of warnings, perhaps using some sort of counting to see how much tests still need to run.

Plans

These are some plans I've dreamt up for react-a11y:

• make rules pluggable like eslint. It would be nice for everyone to be able to write their own rules and inject them into react-a11y. First of all, this would mean less maintenance for me, since poeple can build their own, and it would make react-a11y a formidable validation tool.
• create a nice project page with documentation, because that is what people like these days.
• create filtering options based on rule outputs like affects

Contributing

Interested in contributing? Great! Look here for more info: CONTRIBUTING.md.