@axe-core/puppeteer

Provides a chainable axe API for Puppeteer and automatically injects into all frames.

Previous versions of this program were maintained at dequelabs/axe-puppeteer.

Getting Started

Install Node.js if you haven't already.

Install Puppeteer: npm install puppeteer

Install @axe-core/puppeteer: npm install @axe-core/puppeteer

Usage

This module uses a chainable API to assist in injecting, configuring and analyzing using axe with Puppeteer. As such, it is required to pass an instance of a Puppeteer Page or Frame.

Here is an example of a script that will drive Puppeteer to this repository, perform analysis and then log results to the console.

const { AxePuppeteer } = require('@axe-core/puppeteer');
const puppeteer = require('puppeteer');

(async () => {
  const browser = await puppeteer.launch();
  const page = await browser.newPage();
  await page.goto('https://dequeuniversity.com/demo/mars/');

  try {
    const results = await new AxePuppeteer(page).analyze();
    console.log(results);
  } catch (e) {
    // do something with the error
  }

  await browser.close();
})();

Note: Usage examples make use of ES2017 async/await. Use of await can only be done in a function declared async. If your project does not support async/await, you can just directly use the promise async functions return. Check here for more information.

Bypassing Content Security Policy

When trying to run axe, you might run into issues if the page you are checking has Content Security Policy enabled. To get around this, you must disable it through Page#setBypassCSP before navigating to the site.

loadPage(browser: Browser, url: string, { opts, source }: { opts?: any, source?: string } = {})

An alternate constructor is available which opens a page and performs the CSP bypass for you.

It closes the page after analyze is called.

const { loadPage } = require('@axe-core/puppeteer');
const puppeteer = require('puppeteer');

(async () => {
  const browser = await puppeteer.launch();
  const axeBuilder = await loadPage(
    browser,
    'https://dequeuniversity.com/demo/mars/'
  );
  const results = await axeBuilder.analyze();
  console.log(results);

  await browser.close();
})();

AxePuppeteer(page: Frame | Page[, axeSource: string])

Constructor for the AxePuppeteer helper. You must pass an instance of a Puppeteer Frame or Page as the first argument. Cannot be called without the new keyword.

const builder = new AxePuppeteer(page);

If you wish to run a specific version of axe-core, you can pass the source axe-core source file in as a string. Doing so will mean axe-puppeteer runs this version of axe-core, instead of the one installed as a dependency of axe-puppeteer.

const axeSource = fs.readFileSync('./axe-3.0.js', 'utf8');
const builder = new AxePuppeteer(page, axeSource);

Note that you might need to bypass the Content Security Policy in some cases.

AxePuppeteer#analyze([callback: (Error | null[, Object]) => void])

Performs analysis and passes any encountered error and/or the result object to the provided callback function or promise function. Does not chain as the operation is asynchronous

Using the returned promise (optional):

new AxePuppeteer(page)
  .analyze()
  .then(function (results) {
    console.log(results);
  })
  .catch(err => {
    // Handle error somehow
  });

Using a callback function

new AxePuppeteer(page).analyze(function (err, results) {
  if (err) {
    // Handle error somehow
  }
  console.log(results);
});

AxePuppeteer#include(selector: string | string[])

Adds a CSS selector to the list of elements to include in analysis

new AxePuppeteer(page).include('.results-panel');

AxePuppeteer#exclude(selector: string | string[])

Add a CSS selector to the list of elements to exclude from analysis

new AxePuppeteer(page).include('.results-panel').exclude('.results-panel h2');

AxePuppeteer#options(options: Axe.RunOptions)

Specifies options to be used by axe.run. Will override any other configured options, including calls to withRules and withTags. See axe-core API documentation for information on its structure.

new AxePuppeteer(page).options({
  checks: { 'valid-lang': ['orcish'] }
});

AxePuppeteer#withRules(rules: string | string[])

Limits analysis to only those with the specified rule IDs. Accepts a String of a single rule ID or an Array of multiple rule IDs. Subsequent calls to AxePuppeteer#options, AxePuppeteer#withRules or AxePuppeteer#withRules will override specified options.

new AxePuppeteer(page).withRules('html-lang');

new AxePuppeteer(page).withRules(['html-lang', 'image-alt']);

AxePuppeteer#withTags(tags: string | string[])

Limits analysis to only those with the specified tag or tags. Accepts a String of a single tag or an Array of multiple tags. Subsequent calls to AxePuppeteer#options, AxePuppeteer#withRules or AxePuppeteer#withRules will override specified options.

new AxePuppeteer(page).withTags('wcag2a');

new AxePuppeteer(page).withTags(['wcag2a', 'wcag2aa']);

AxePuppeteer#disableRules(rules: string | string[])

Skips verification of the rules provided. Accepts a String of a single rule ID or an Array of multiple rule IDs. Subsequent calls to AxePuppeteer#options, AxePuppeteer#disableRules will override specified options.

new AxePuppeteer(page).disableRules('color-contrast');

or use it combined with some specified tags:

new AxePuppeteer(page)
  .withTags(['wcag2a', 'wcag2aa'])
  .disableRules('color-contrast');

AxePuppeteer#disableFrame(selector: string)

Skips specific frame with selector provided. Accepts a String of a single selector. Subsequent calls to AxePuppeteer#options, AxePuppeteer#disableFrame will override specified options.

new AxePuppeteer(page).disableFrame('#my-frame');

or use it combined with some specified tags:

new AxePuppeteer(page)
  .withTags(['wcag2a', 'wcag2aa'])
  .disableFrame('#my-frame');

AxePuppeteer#configure(config: Axe.Spec)

Inject an axe configuration object to modify the ruleset before running Analyze. Subsequent calls to this method will invalidate previous ones by calling axe.configure and replacing the config object. See axe-core API documentation for documentation on the object structure.

const config = {
  checks: [Object],
  rules: [Object]
};
const results = await new AxePuppeteer(page).configure(config).analyze();
console.log(results);

AxePuppeteer#setLegacyMode(legacyMode: boolean = true)

Set the frame testing method to "legacy mode". In this mode, axe will not open a blank page in which to aggregate its results. This can be used in an environment where opening a blank page is causes issues.

With legacy mode turned on, axe will fall back to its test solution prior to the 4.3 release, but with cross-origin frame testing disabled. The frame-tested rule will report which frames were untested.

Important Use of .setLegacyMode() is a last resort. If you find there is no other solution, please report this as an issue.

const axe = new AxePuppeteer(page).setLegacyMode();
const result = await axe.analyze();
axe.setLegacyMode(false); // Disables legacy mode

Caveat

Due to axe-core needing to be injected into the page and executed we are unable to do the following:

await page.setJavaScriptEnabled(false);