axe-core

Axe is an accessibility testing engine for websites and other HTML-based user interfaces. It's fast, secure, lightweight, and was built to seamlessly integrate with any existing test environment so you can automate accessibility testing alongside your regular functional testing.

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The Accessibility Rules

Axe-core has different types of rules, for WCAG 2.0, 2.1, 2.2 on level A, AA and AAA as well as a number of best practices that help you identify common accessibility practices like ensuring every page has an h1 heading, and to help you avoid "gotchas" in ARIA like where an ARIA attribute you used will get ignored. The complete list of rules, grouped WCAG level and best practice, can be found in doc/rule-descriptions.md.

With axe-core, you can find on average 57% of WCAG issues automatically. Additionally, axe-core will return elements as "incomplete" where axe-core could not be certain, and manual review is needed.

To catch bugs earlier in the development cycle we recommend using the axe-linter vscode extension. To improve test coverage even further we recommend the intelligent guided tests in the axe Extension.

Getting started

First download the package:

npm install axe-core --save-dev

Or, using pnpm:

pnpm add --save-dev axe-core

Now include the javascript file in each of your iframes in your fixtures or test systems:

<script src="node_modules/axe-core/axe.min.js"></script>

Now insert calls at each point in your tests where a new piece of UI becomes visible or exposed:

axe
  .run()
  .then(results => {
    if (results.violations.length) {
      throw new Error('Accessibility issues found');
    }
  })
  .catch(err => {
    console.error('Something bad happened:', err.message);
  });

Philosophy

The web can only become an accessible, inclusive space if developers are empowered to take responsibility for accessibility testing and accessible coding practices.

Automated accessibility testing is a huge timesaver, it doesn't require special expertise, and it allows teams to focus expert resources on the accessibility issues that really need them. Unfortunately, most accessibility tools are meant to be run on sites and applications that have reached the end of the development process and often don't give clear or consistent results, causing frustration and delays just when you thought your product was ready to ship.

Axe was built to reflect how web development actually works. It works with all modern browsers, tools, and testing environments a dev team might use. With axe, accessibility testing can be performed as part of your unit testing, integration testing, browser testing, and any other functional testing your team already performs on a day-to-day basis. Building accessibility testing into the early development process saves time, resources, and all kinds of frustration.

About axe - our Manifesto

• Axe is open source.
• It returns zero false positives (bugs notwithstanding).
• It's designed to work on all modern browsers and with whatever tools, frameworks, libraries and environments you use today.
• It's actively supported by Deque Systems, a major accessibility vendor.
• It integrates with your existing functional/acceptance automated tests.
• It automatically determines which rules to run based on the evaluation context.
• Axe supports in-memory fixtures, static fixtures, integration tests, and iframes of infinite depth.
• Axe is highly configurable.

Supported Browsers

The axe-core API fully supports the following browsers:

• Microsoft Edge v40 and above
• Google Chrome v42 and above
• Mozilla Firefox v38 and above
• Apple Safari v7 and above
• Internet Explorer v11 (DEPRECATED)

Support means that we will fix bugs and attempt to test each browser regularly. Only Chrome and Firefox are currently tested on every pull request.

There is limited support for JSDOM. We will attempt to make all rules compatible with JSDOM but where this is not possible, we recommend turning those rules off. Currently the color-contrast rule is known not to work with JSDOM.

We can only support environments where features are either natively supported or polyfilled correctly. We do not support the deprecated v0 Shadow DOM implementation.

Contents of the API Package

The axe-core API package consists of:

• axe.js - the JavaScript file that should be included in your web site under test (API)
• axe.min.js - a minified version of the above file

This is the beginning of the README. Read the rest at the original. Read the full README ↗