eslint-plugin-jsx-a11y
Advanced tools
Package description
The eslint-plugin-jsx-a11y npm package is a collection of accessibility-related rules for ESLint that enforce best practices for accessibility in JSX (most commonly used with React). It helps developers write code that is accessible to users with disabilities by checking for common accessibility errors and suggesting improvements.
Accessible elements
Ensures interactive elements are accessible. For example, this rule checks that buttons have an accessible name and can be interacted with via keyboard.
<button onClick={this.handleClick}>Click me</button>Aria roles
Enforces the use of valid ARIA roles and that elements with ARIA roles have the required attributes for that role.
<div role="button" onClick={this.handleRoleClick}>Role Button</div>Media captions
Ensures media elements such as audio and video have captions or descriptions to aid users who cannot see or hear the content.
<video><track kind="captions" /></video>No redundant alt text
Prevents the use of redundant alt text in images, which can be frustrating for screen reader users.
<img src="image.jpg" alt="" />Keyboard accessibility
Ensures that custom interactive elements are focusable and have keyboard event handlers to mimic native interactive elements.
<div tabIndex="0" onKeyDown={this.handleKeyDown}>Focusable Div</div>Similar to eslint-plugin-jsx-a11y, but specifically tailored for Vue.js applications. It provides a set of accessibility rules for Vue.js templates.
While not exclusively focused on accessibility, eslint-plugin-react includes some rules related to accessibility. It is a broader linting tool for React-specific code practices.
Although not an ESLint plugin, axe-core is a library for accessibility testing that can be integrated into testing frameworks. It provides comprehensive accessibility checks that can be run on rendered HTML, complementing the static analysis provided by eslint-plugin-jsx-a11y.
Readme
Static AST checker for accessibility rules on JSX elements.
Ryan Florence built out this awesome runtime-analysis tool called react-a11y. It is super useful. However, since you're probably already using linting in your project, this plugin comes for free and closer to the actual development process. Pairing this plugin with an editor lint plugin, you can bake accessibility standards into your application in real-time.
Note: This project does not replace react-a11y, but can and should be used in conjunction with it. Static analysis tools cannot determine values of variables that are being placed in props before runtime, so linting will not fail if that value is undefined and/or does not pass the lint rule.
If you are installing this plugin via eslint-config-airbnb, please follow these instructions.
You'll first need to install ESLint:
# npm
npm install eslint --save-dev
# yarn
yarn add eslint --dev
Next, install eslint-plugin-jsx-a11y:
# npm
npm install eslint-plugin-jsx-a11y --save-dev
# yarn
yarn add eslint-plugin-jsx-a11y --dev
Note: If you installed ESLint globally (using the -g flag in npm, or the global prefix in yarn) then you must also install eslint-plugin-jsx-a11y globally.
Add jsx-a11y to the plugins section of your .eslintrc configuration file. You can omit the eslint-plugin- prefix:
{
"plugins": [
"jsx-a11y"
]
}
Then configure the rules you want to use under the rules section.
{
"rules": {
"jsx-a11y/rule-name": 2
}
}
You can also enable all the recommended or strict rules at once.
Add plugin:jsx-a11y/recommended or plugin:jsx-a11y/strict in extends:
{
"extends": [
"plugin:jsx-a11y/recommended"
]
}
aria-* props are valid.h1, h2, etc) elements contain accessible content.href prop value is not just #.<html> element has lang prop.<img> alt prop does not contain the word "image", "picture", or "photo".onClick must be focusable.<label> elements have the htmlFor prop.<audio> and <video> elements must have a <track> for captions.onMouseOver/onMouseOut are accompanied by onFocus/onBlur for keyboard-only users.accessKey prop is not used on any element to avoid complications with keyboard commands used by a screenreader.tabIndex should only be declared on interactive elements.onBlur over onChange on select menus for accessibility.<div>) that have click handlers use the role attribute.aria-* properties supported by that role.scope prop is only used on <th> elements.tabIndex value is not greater than zero.The following rules have extra options when in recommended mode:
'jsx-a11y/no-interactive-element-to-noninteractive-role': [
'error',
{
tr: ['none', 'presentation'],
},
]
'jsx-a11y/no-noninteractive-element-interactions': [
'error',
{
handlers: [
'onClick',
'onMouseDown',
'onMouseUp',
'onKeyPress',
'onKeyDown',
'onKeyUp',
],
},
]
'jsx-a11y/no-noninteractive-element-to-interactive-role': [
'error',
{
ul: [
'listbox',
'menu',
'menubar',
'radiogroup',
'tablist',
'tree',
'treegrid',
],
ol: [
'listbox',
'menu',
'menubar',
'radiogroup',
'tablist',
'tree',
'treegrid',
],
li: ['menuitem', 'option', 'row', 'tab', 'treeitem'],
table: ['grid'],
td: ['gridcell'],
},
]
'jsx-a11y/no-noninteractive-tabindex': [
'error',
{
tags: [],
roles: ['tabpanel'],
},
]
'jsx-a11y/no-noninteractive-element-interactions': [
'error',
{
handlers: [
'onClick',
'onMouseDown',
'onMouseUp',
'onKeyPress',
'onKeyDown',
'onKeyUp',
],
},
]
If you are developing new rules for this project, you can use the create-rule
script to scaffold the new files.
$ ./scripts/create-rule.js my-new-rule
An operating system will provide an accessibility API that maps application state and content onto input/output controllers such as a screen reader, braille device, keyboard, etc.
These APIs were developed as computer interfaces shifted from buffers (which are text based and inherently quite accessible) to graphical user interfaces (GUIs). The first attempts to make GUIs accessible involved raster image parsing to recognize characters, words, etc. This information was stored in a parallel buffer and made accessible to assistive technology (AT) devices.
As GUIs became more complex, the raster parsing approach became untenable. Accessibility APIs were developed to replace them. Check out NSAccessibility (AXAPI) for an example. See Core Accessibility API Mappings 1.1 for more details.
Browsers support an Accessibility API on a per operating system basis. For instance Firefox implements the MSAA accessibility API on Windows, but does not implement the AXAPI on OSX.
From the W3 Core Accessibility API Mappings 1.1
The accessibility tree and the DOM tree are parallel structures. Roughly speaking the accessibility tree is a subset of the DOM tree. It includes the user interface objects of the user agent and the objects of the document. Accessible objects are created in the accessibility tree for every DOM element that should be exposed to an assistive technology, either because it may fire an accessibility event or because it has a property, relationship or feature which needs to be exposed. Generally if something can be trimmed out it will be, for reasons of performance and simplicity. For example, a with just a style change and no semantics may not get its own accessible object, but the style change will be exposed by other means.
Browser vendors are beginning to expose the AX Tree through inspection tools. Chrome has an experiment available to enable their inspection tool.
You can also see a text-based version of the AX Tree in Chrome in the stable release version.
chrome://accessibility/ in Chrome.accessibility off link for any tab that you want to inspect.show accessibility tree will appear; click this link.A browser constructs an AX Tree as a subset of the DOM. ARIA heavily informs the properties of this AX Tree. This AX Tree is exposed to the system level Accessibility API which mediates assistive technology agents.
We model ARIA in the aria-query project. We model AXObjects (that comprise the AX Tree) in the axobject-query project. The goal of the WAI-ARIA specification is to be a complete complete declarative interface to the AXObject model. The in-draft 1.2 version is moving towards this goal. But until then, we must consider the semantics constructs affored by ARIA as well as those afforded by the AXObject model (AXAPI) in order to determine how HTML can be used to express user interface affordances to assistive technology users.
eslint-plugin-jsx-a11y is licensed under the MIT License.
FAQs
Static AST checker for accessibility rules on JSX elements.
The npm package eslint-plugin-jsx-a11y receives a total of 12,531,059 weekly downloads. As such, eslint-plugin-jsx-a11y popularity was classified as popular.
We found that eslint-plugin-jsx-a11y demonstrated a healthy version release cadence and project activity because the last version was released less than a year ago. It has 4 open source maintainers collaborating on the project.
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