Pa11y is an automated accessibility testing tool that helps developers ensure their web applications meet accessibility standards. It can be used to run accessibility tests on web pages and generate reports on any issues found.
Run Accessibility Tests
This feature allows you to run accessibility tests on a given URL. The results will include any accessibility issues found on the page.
const pa11y = require('pa11y');
(async () => {
const results = await pa11y('https://example.com');
console.log(results);
})();Custom Configuration
Pa11y allows you to customize the accessibility tests by specifying standards (like WCAG2AA) and other options such as taking a screenshot of the page.
const pa11y = require('pa11y');
(async () => {
const results = await pa11y('https://example.com', {
standard: 'WCAG2AA',
screenCapture: './screenshot.png'
});
console.log(results);
})();Programmatic API
You can use Pa11y's programmatic API to perform actions on the page before running the accessibility tests. This is useful for testing dynamic content.
const pa11y = require('pa11y');
(async () => {
const results = await pa11y('https://example.com', {
actions: [
'click element #button',
'wait for element #result to be visible'
]
});
console.log(results);
})();Axe-core is a popular accessibility testing engine for websites and other HTML-based user interfaces. It provides a comprehensive set of rules for accessibility testing and can be integrated into various testing frameworks. Compared to Pa11y, axe-core is more focused on providing a robust rule set and is often used as a library within other tools.
Accessibility Insights for Web is a tool that helps developers find and fix accessibility issues in web applications. It provides a browser extension and a CLI for automated testing. Compared to Pa11y, Accessibility Insights offers a more user-friendly interface and additional guidance on fixing issues.
Cypress-axe is a plugin for the Cypress end-to-end testing framework that integrates axe-core for accessibility testing. It allows you to run accessibility checks as part of your Cypress test suite. Compared to Pa11y, cypress-axe is more suitable for developers already using Cypress for their testing needs.
Pa11y is your automated accessibility testing pal. It runs HTML CodeSniffer from the command line for programmatic accessibility reporting.
On the command line:
pa11y example.com
In JavaScript:
var pa11y = require('pa11y');
var test = pa11y(options);
test.run('example.com', function (error, results) {
/* ... */
});
Need a GUI? Try Koa11y!
We're pleased to announce the Pa11y 5.0 beta is now available! We're switching from PhantomJS to Headless Chrome, as well as many other changes. See the migration guide for further details.
If you'd like to try out the Pa11y 5.0 beta you can do so with
npm install -g pa11y@beta
Feedback is greatly appreciated 😊
Pa11y requires Node.js 4+ to run.
On a Mac, you can install the required dependency with Homebrew:
$ brew install node
Alternatively download pre-built packages from the Node.js website.
Depending on your flavour of Linux, you should be able to use a package manager to install the required dependency. Alternatively download pre-built packages from the Node.js website.
On Windows 10, download a pre-built package from the Node.js website. Pa11y will be usable via the bundled Node.js application as well as the Windows command prompt.
Windows 7 and below users approach with caution – we've been able to get Pa11y running but only after installing Visual Studio and the Windows SDK (as well as Git, and Python). The Windows installation instructions for node-gyp are a good place to start. If you have had a better experience than this then please do share!
Install Pa11y globally with npm:
npm install -g pa11y
This installs the pa11y command-line tool:
Usage: pa11y [options] <url>
Options:
-h, --help output usage information
-V, --version output the version number
-n, --environment output details about the environment Pa11y will run in
-s, --standard <name> the accessibility standard to use: Section508, WCAG2A, WCAG2AA (default), WCAG2AAA
-r, --reporter <reporter> the reporter to use: cli (default), csv, tsv, html, json
-l, --level <level> the level of message to fail on (exit with code 2): error, warning, notice
-T, --threshold <number> permit this number of errors, warnings, or notices, otherwise fail with exit code 2
-i, --ignore <ignore> types and codes of messages to ignore, a repeatable value or separated by semi-colons
-R, --root-element <selector> a CSS selector used to limit which part of a page is tested
-E, --hide-elements <hide> a CSS selector to hide elements from testing, selectors can be comma separated
-c, --config <path> a JSON or JavaScript config file
-p, --port <port> the port to run PhantomJS on
-t, --timeout <ms> the timeout in milliseconds
-w, --wait <ms> the time to wait before running tests in milliseconds
-v, --verify-page <string> HTML string to verify is present in the page source HTML
-d, --debug output debug messages
-H, --htmlcs <url> the URL or path to source HTML_CodeSniffer from
-e, --phantomjs <path> the path to the phantomjs executable
-S, --screen-capture <path> a path to save a screen capture of the page to
-A, --add-rule <rule> WCAG 2.0 rules from a different standard to include, a repeatable value or separated by semi-colons
Run an accessibility test against a URL:
pa11y http://example.com
Run an accessibility test against a file (absolute paths only, not relative):
pa11y file:///path/to/your/file.html
Run a test with CSV reporting and save to a file:
pa11y --reporter csv http://example.com > report.csv
Run a test with TSV reporting and save to a file:
pa11y --reporter tsv http://example.com > report.tsv
Run Pa11y with the Section508 ruleset:
pa11y --standard Section508 http://example.com
The command-line tool uses the following exit codes:
0: Pa11y ran successfully, and there are no errors1: Pa11y failed run due to a technical fault2: Pa11y ran successfully but there are errors in the pageBy default, only accessibility issues with a type of error will exit with a code of 2. This is configurable with the --level flag which can be set to one of the following:
error: exit with a code of 2 on errors only, exit with a code of 0 on warnings and noticeswarning: exit with a code of 2 on errors and warnings, exit with a code of 0 on noticesnotice: exit with a code of 2 on errors, warnings, and noticesnone: always exit with a code of 0The command-line tool can be configured with a JSON file as well as arguments. By default it will look for a pa11y.json file in the current directory, but you can change this with the --config flag:
pa11y --config ./path/to/config.json http://example.com
For more information on configuring Pa11y, see the configuration documentation.
The ignore flag can be used in several different ways. Separated by semi-colons:
pa11y --ignore "warning;notice" http://example.com
or by using the flag multiple times:
pa11y --ignore warning --ignore notice http://example.com
Pa11y can also ignore notices, warnings, and errors up to a threshold number. This might be useful if you're using CI and don't want to break your build. The following example will return exit code 0 on a page with 9 errors, and return exit code 2 on a page with 10 or more errors.
pa11y --threshold 10 http://example.com
The command-line tool can report test results in a few different ways using the --reporter flag. The built-in reporters are:
cli: output test results in a human-readable formatcsv: output test results as comma-separated valuestsv: output test results as tab-separated valueshtml: output test results as an HTML documentjson: output test results as a JSON arraymarkdown: output test results as a Markdown documentYou can also write and publish your own reporters. Pa11y looks for reporters in the core library, your node_modules folder (with a naming pattern), and the current working directory. The first reporter found will be loaded. So with this command:
pa11y --reporter rainbows http://example.com
The following locations will be checked:
<pa11y-core>/reporter/rainbows
<cwd>/node_modules/pa11y-reporter-rainbows
<cwd>/rainbows
A Pa11y reporter should export the following methods, and these should make use of console to send output:
begin(url); // Called when pa11y starts
error(message); // Called when a technical error is reported
debug(message); // Called when a debug message is reported
info(message); // Called when an information message is reported
results(resultsArray, url); // Called with the results of a test run
Reporters may also optionally export a process method. This should accept the same arguments as the results method but return the processed results rather than outputting them:
process(resultsArray, url); // Called with results by a user
Install Pa11y with npm or add to your package.json:
npm install pa11y
Require Pa11y:
var pa11y = require('pa11y');
Create a tester by initialising Pa11y with some options:
var test = pa11y(options);
The test.run function can then be used to run your test function against a URL:
test.run('http://www.example.com/', function(error, results) {
// ...
});
The results that get passed into your test callback come from HTML CodeSniffer, and look like this:
[
{
code: 'WCAG2AA.Principle1.Guideline1_1.1_1_1.H30.2',
context: '<a href="http://example.com/"><img src="example.jpg" alt=""/></a>',
message: 'Img element is the only content of the link, but is missing alt text. The alt text should describe the purpose of the link.',
selector: 'html > body > p:nth-child(1) > a',
type: 'error',
typeCode: 1
},
{
code: 'WCAG2AA.Principle1.Guideline1_3.1_3_1.H49.B',
context: '<b>Hello World!</b>',
message: 'Semantic markup should be used to mark emphasised or special text so that it can be programmatically determined.',
selector: '#content > b:nth-child(4)',
type: 'warning',
typeCode: 2
},
{
code: 'WCAG2AA.Principle2.Guideline2_4.2_4_4.H77,H78,H79,H80,H81',
context: '<a href="http://example.com/">Hello World!</a>',
message: 'Check that the link text combined with programmatically determined link context identifies the purpose of the link.',
selector: 'html > body > ul > li:nth-child(2) > a',
type: 'notice',
typeCode: 3
}
]
If you wish to transform these results with the command-line reporters, then you can do so in your code by requiring them in. The csv, tsv, html, json, and markdown reporters all expose a process method:
// Assuming you've already run tests, and the results
// are available in a `results` variable:
var htmlReporter = require('pa11y/reporter/html');
var html = htmlReporter.process(results, url);
Pa11y exposes a function which allows you to validate action strings before attempting to use them.
This function accepts an action string and returns a boolean indicating whether it matches one of the actions that Pa11y supports:
pa11y.validateAction('click element #submit'); // true
pa11y.validateAction('open the pod bay doors'); // false
Pa11y has lots of options you can use to change the way PhantomJS runs, or the way your page is loaded. Options can be set either on the Pa11y instance when it's created or the individual test runs. This allows you to set some defaults which can be overridden per-test:
// Set the default Foo header to "bar"
var test = pa11y({
page: {
headers: {
Foo: 'bar'
}
}
});
// Run a test with the Foo header set to "bar"
test.run('http://www.example.com/', function(error, results) { /* ... */ });
// Run a test with the Foo header overridden
test.run('http://www.example.com/', {
page: {
headers: {
Foo: 'hello'
}
}
}, function(error, results) { /* ... */ });
Below is a reference of all the options that are available:
actions (array) BETAActions to be run before Pa11y tests the page. There are quite a few different actions available in Pa11y, the Actions documentation outlines each of them.
Note: actions are currently in a beta state and the API may change while we gather feedback.
pa11y({
actions: [
'set field #username to exampleUser',
'set field #password to password1234',
'click element #submit',
'wait for path to be /myaccount'
]
});
Defaults to an empty array.
allowedStandards (array)The accessibility standards that are allowed to be used. This can be modified to allow for custom HTML CodeSniffer standards.
pa11y({
allowedStandards: ['WCAG2AA', 'My Custom Standard']
});
Defaults to Section508, WCAG2A, WCAG2AA, and WCAG2AAA.
beforeScript (function)Note: unless you're doing something particularly complicated, it's much easier and less error prone to use actions rather than beforeScript. If you specify both, the beforeScript will be dropped with a warning.
A function to be run before Pa11y tests the page. The function accepts three parameters:
page is the phantomjs page object, documentation for the phantom bridge can be found hereoptions is the finished options object used to configure pa11ynext is a callback functionpa11y({
beforeScript: function(page, options, next) {
// Make changes to the page
// When finished call next to continue running Pa11y tests
next();
}
});
Defaults to null.
hideElements (string)A CSS selector to hide elements from testing, selectors can be comma separated.
Elements matching this selector will be hidden from testing by styling them with visibility:hidden.
pa11y({
hideElements: '.advert, #modal, div[aria-role=presentation]'
});
htmlcs (string)The path or URL to source HTML CodeSniffer from.
pa11y({
htmlcs: 'http://squizlabs.github.io/HTML_CodeSniffer/build/HTMLCS.js'
});
Defaults to a local copy of HTML CodeSniffer, found in lib/vendor/HTMLCS.js.
ignore (array)An array of result codes and types that you'd like to ignore. You can find the codes for each rule in the console output and the types are error, warning, and notice.
pa11y({
ignore: [
'notice',
'WCAG2AA.Principle3.Guideline3_1.3_1_1.H57.2'
]
});
Defaults to an empty array.
log (object)An object which implements the methods debug, error, and info which will be used to report errors and test information.
pa11y({
log: {
debug: console.log.bind(console),
error: console.error.bind(console),
info: console.info.bind(console)
}
});
Each of these defaults to an empty function.
page.headers (object)A key-value map of request headers to send when testing a web page.
pa11y({
page: {
headers: {
Cookie: 'foo=bar'
}
}
});
Defaults to an empty object.
page.settings (object)A key-value map of settings to add to the PhantomJS page. For a full list of available settings, see the PhantomJS page settings documentation.
pa11y({
page: {
settings: {
loadImages: false,
userName: 'nature',
password: 'say the magic word'
}
}
});
Defaults to:
{
userAgent: 'pa11y/<version> (truffler/<version>)'
}
page.viewport (object)The viewport width and height in pixels. The viewport object must have both width and height properties.
pa11y({
page: {
viewport: {
width: 320,
height: 480
}
}
});
Defaults to:
{
width: 1024,
height: 768
}
phantom (object)A key-value map of settings to initialise PhantomJS with. This is passed directly into the phantom module – documentation can be found here. You can pass PhantomJS command-line parameters in the phantom.parameters option as key-value pairs.
pa11y({
phantom: {
port: 1234,
parameters: {
'ignore-ssl-errors': 'false',
'ssl-protocol': 'tlsv1'
}
}
});
Defaults to:
{
parameters: {
'ignore-ssl-errors': 'true'
}
}
If phantom.port is not specified, a random available port will be used.
rootElement (element)The root element for testing a subset of the page opposed to the full document.
pa11y({
rootElement: '#main'
});
Defaults to null, meaning the full document will be tested.
rules (array)An array of WCAG 2.0 guidelines that you'd like to include to the current standard. Note: THese won't be applied to Section508 standard. You can find the codes for each guideline in the HTML Code Sniffer WCAG2AAA ruleset .
pa11y({
rules: [
'Principle1.Guideline1_3.1_3_1_AAA'
]
});
screenCapture (string)A file path to save a screen capture of the tested page to. The screen will be captured immediately after the Pa11y tests have run so that you can verify that the expected page was tested.
pa11y({
screenCapture: __dirname + '/my-screen-capture.png'
});
Defaults to null, meaning the screen will not be captured.
standard (string)The accessibility standard to use when testing pages. This should be one of Section508, WCAG2A, WCAG2AA, or WCAG2AAA (or match one of the standards in the allowedStandards option).
pa11y({
standard: 'Section508'
});
Defaults to WCAG2AA.
timeout (number)The time in milliseconds that a test should be allowed to run before calling back with a timeout error.
pa11y({
timeout: 500
});
Defaults to 30000.
wait (number)The time in milliseconds to wait before running HTML CodeSniffer on the page.
pa11y({
wait: 500
});
Defaults to 0.
verifyPage (string)HTML string to verify is present in the page source HTML. Could be used to ascertain that intended page is being tested (as opposed to error page) by using <title> tags and content (as below), or that a specific element is present.
pa11y({
verifyPage: '<title>Nature Research: science journals, jobs, information and services.</title>'
});
Defaults to null.
Actions are additional interactions that you can make Pa11y perform before the tests are run. They allow you to do things like click on a button, enter a value in a form, wait for a redirect, or wait for the URL fragment to change:
pa11y({
actions: [
'click element #tab-1',
'wait for element #tab-1-content to be visible',
'set field #fullname to John Doe',
'check field #terms-and-conditions',
'uncheck field #subscribe-to-marketing',
'wait for fragment to be #page-2',
'wait for path to not be /login',
'wait for url to be https://example.com/'
]
});
Below is a reference of all the available actions and what they do on the page. Some of these take time to complete so you may need to increase the timeout option if you have a large set of actions.
This allows you to click an element by passing in a CSS selector. This action takes the form click element <selector>. E.g.
pa11y({
actions: [
'click element #tab-1'
]
});
You can use any valid query selector, including classes and types.
This allows you to set the value of a text-based input or select box by passing in a CSS selector and value. This action takes the form set field <selector> to <value>. E.g.
pa11y({
actions: [
'set field #fullname to John Doe'
]
});
This allows you to check or uncheck checkbox and radio inputs by passing in a CSS selector. This action takes the form check field <selector> or uncheck field <selector>. E.g.
pa11y({
actions: [
'check field #terms-and-conditions',
'uncheck field #subscribe-to-marketing'
]
});
This allows you to pause the test until a condition is met, and the page has either a given fragment, path, or URL. This will wait until Pa11y times out so it should be used after another action that would trigger the change in state. You can also wait until the page does not have a given fragment, path, or URL using the to not be syntax. This action takes one of the forms:
wait for fragment to be <fragment> (including the preceding #)wait for fragment to not be <fragment> (including the preceding #)wait for path to be <path> (including the preceding /)wait for path to not be <path> (including the preceding /)wait for url to be <url>wait for url to not be <url>E.g.
pa11y({
actions: [
'click element #login-link',
'wait for path to be /login'
]
});
This allows you to pause the test until an element on the page (matching a CSS selector) is either added, removed, visible, or hidden. This will wait until Pa11y times out so it should be used after another action that would trigger the change in state. This action takes one of the forms:
wait for element <selector> to be addedwait for element <selector> to be removedwait for element <selector> to be visiblewait for element <selector> to be hiddenE.g.
pa11y({
actions: [
'click element #tab-2',
'wait for element #tab-1 to be hidden'
]
});
Run Pa11y on a URL and output the results. See the example, or run it with:
node example/basic
Use async to run Pa11y on multiple URLs in series, and output the results. See the example, or run it with:
node example/multiple
Use async to run Pa11y on multiple URLs in parallel, with a configurable concurrency. Then output the results. See the example, or run it with:
node example/multiple-concurrent
Step through some actions before Pa11y runs. This example logs into a fictional site then waits until the account page has loaded before running Pa11y. See the example.
Inject a script before Pa11y runs. This example logs into a fictional site then waits until the account page has loaded before running Pa11y. See the example.
See our Troubleshooting guide to get the answers to common questions about Pa11y, along with some ideas to help you troubleshoot any problems.
Here are some useful articles written by Pa11y users and contributors:
There are many ways to contribute to Pa11y, we cover these in the contributing guide for this repo.
If you're ready to contribute some code, clone this repo locally and commit your code on a new branch.
Please write unit tests for your code, and check that everything works by running the following before opening a PR:
make ci
You can also run verifications and tests individually:
make verify # Verify all of the code (ESLint)
make test # Run all tests
make test-unit # Run the unit tests
make test-unit-coverage # Run the unit tests with coverage
make test-integration # Run the integration tests
Pa11y major versions are normally supported for 6 months after their last minor release. This means that patch-level changes will be added and bugs will be fixed. The table below outlines the end-of-support dates for major versions, and the last minor release for that version.
We also maintain a migration guide to help you migrate.
| :grey_question: | Major Version | Last Minor Release | Node.js Versions | Support End Date |
|---|---|---|---|---|
| :heart: | 4 | N/A | 4+ | N/A |
| :skull: | 3 | 3.8 | 0.12–6 | 2016-12-05 |
| :skull: | 2 | 2.4 | 0.10–0.12 | 2016-10-16 |
| :skull: | 1 | 1.7 | 0.10 | 2016-06-08 |
If you're opening issues related to these, please mention the version that the issue relates to.
Pa11y is licensed under the Lesser General Public License (LGPL-3.0).
Copyright © 2013–2017, Team Pa11y and contributors
4.13.2 (2017-11-26)
FAQs
Pa11y is your automated accessibility testing pal
The npm package pa11y receives a total of 65,691 weekly downloads. As such, pa11y popularity was classified as popular.
We found that pa11y demonstrated a healthy version release cadence and project activity because the last version was released less than a year ago. It has 9 open source maintainers collaborating on the project.
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