Accessibility styleguide ready
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"
orrole="alert"
aria-live
androle
props may be exposed where appropriate in grafana/ui components- Only use
aria-live="assertive"
orrole="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 onhttp://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.