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Accessibility styleguide
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At Grafana we pay special attention to accessibility and that's why it's important that all components are written with it in mind.

The goal of this document is to list best practices and recommendations when it comes to writing accessible components.

Grafana/UI components​

Some grafana/ui components have specific mechanisms built-in that make it easier to write accessible components.

Form elements​

One of the important accessibility considerations when working with form elements is to make sure form controls are properly labelled. For that a label element has to be associated with the respective form control. One way to do that is to provide for attribute to the label that matches the id attribute of the form control.

The form components from grafana/ui provide an easier way to achieve that. The form elements, used inside Field components, will get the label properly associated with them given that the element has id (in case of Select the prop is inputId) specified.

As an example, this code

<Field label="Name">
  <Input id="name" placeholder="Enter a name" />
</Field>

will be rendered as (simplified)

<div>
  <label for="name"> Name </label>
  <input name="name" type="text" id="name" placeholder="Enter a name" value="" />
</div>

As long as the form element has a unique id attribute specified, it will be automatically accessible when rendered.

aria-live guidelines​

aria-live should be used sparingly, as it may result in an overflow of announcements for screen reader users. The main responsibility for handling aria-live should be with the consumers, where the correct tools should be provided by grafana/ui.

  • Grafana/ui components should not contain aria-live="assertive" or role="alert"
  • aria-live and role props may be exposed where appropriate in grafana/ui components
  • Only use aria-live="assertive" or role="alert" to provide critical feedback to a direct user action (e.g. user typing in search and there are no further results from the query)
  • Use aria-live="polite" for areas that are updated by a user action not directly related to the element

Writing tests with accessibility in mind​

We use React Testing Library (RTL) for writing unit tests. The library is built with accessibility in mind and makes it easier to ensure the written code is accessible to all users. When querying DOM elements with RTL prefer using *ByRole queries as they resemble closely how the users interact with the page - both using mouse/visual display and assistive technologies. As a rule of thumb, if code is written with the accessibility concerns in mind, *ByRole queries will be sufficient in most of the cases. There are certainly exceptions here, as not all the elements have defined ARIA role.

As an example, for this code

<Field label="Username">
  <Input id="username" placeholder="Enter a name" value={'Test'} />
</Field>

the test case could be as follows

it('has username set', () => {
  expect(screen.getByRole('textbox', { name: 'Username' })).toHaveValue('Test');
});

Input with type text (default type value) has a role of textbox and the name option is not the name attribute given to the input elements but their accessible name, which in this case is the text content of the associated with input label.

Pull requests that introduce accessibility(a11y) errors:​

We use pa11y-ci to collect accessibility errors on some URLs in the project, threshold errors are specified per URL.

If the contribution introduces new a11y errors, our continuous integration will fail, preventing you to merge to the main branch. In those cases there are two alternatives for moving forward:

  • Check the error log on the pipeline step test-a11y-frontend-pr, identify what was the error, and fix it.
  • Locally run the command yarn test:accessibility-report that generates an HTML accessibility report, then go to the URL that contains your change, identify the error, and fix it. Keep in mind, a local e2e Grafana instance is going to be running on http://localhost:3001.

You can also prevent introducing a11y errors by installing an a11y plugin in your browser, for example, axe DevTools, Accessibility Insights for Web among others.