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325 lines
13 KiB
Markdown
325 lines
13 KiB
Markdown
---
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stage: none
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group: unassigned
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info: Any user with at least the Maintainer role can merge updates to this content. For details, see https://docs.gitlab.com/development/development_processes/#development-guidelines-review.
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title: Accessibility best practices
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---
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## Quick summary
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Since [no ARIA is better than bad ARIA](https://w3c.github.io/aria-practices/#no_aria_better_bad_aria),
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review the following recommendations before using `aria-*`, `role`, and `tabindex`.
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Use semantic HTML, which has accessibility semantics baked in, and ideally test with
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[relevant combinations of screen readers and browsers](https://www.accessibility-developer-guide.com/knowledge/screen-readers/relevant-combinations/).
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In [WebAIM's accessibility analysis of the top million home pages](https://webaim.org/projects/million/#aria),
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they found that "ARIA correlated to higher detectable errors".
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It is likely that misuse of ARIA is a big cause of increased errors,
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so when in doubt don't use `aria-*`, `role`, and `tabindex` and stick with semantic HTML.
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## Enable keyboard navigation on macOS
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By default, macOS limits the <kbd>tab</kbd> key to **Text boxes and lists only**. To enable full keyboard navigation:
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1. Open **System Preferences**.
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1. Select **Keyboard**.
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1. Open the **Shortcuts** tab.
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1. Enable the setting **Use keyboard navigation to move focus between controls**.
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You can read more about enabling browser-specific keyboard navigation on [a11yproject](https://www.a11yproject.com/posts/macos-browser-keyboard-navigation/).
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## Quick checklist
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- [Text](https://design.gitlab.com/components/text-input#accessibility),
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[textarea](https://design.gitlab.com/components/textarea#accessibility),
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[select](https://design.gitlab.com/components/select#accessibility),
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[checkbox](https://design.gitlab.com/components/checkbox#accessibility),
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[radio](https://design.gitlab.com/components/radio-button#accessibility),
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[file](#form-inputs-with-accessible-names),
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and [toggle](https://design.gitlab.com/components/toggle#accessibility) inputs have accessible names.
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- [Buttons](#buttons-and-links-with-descriptive-accessible-names),
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[links](#buttons-and-links-with-descriptive-accessible-names),
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and [images](#images-with-accessible-names) have descriptive accessible names.
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- Icons
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- [Non-decorative icons](#icons-that-convey-information) have an `aria-label`.
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- [Clickable icons](#icons-that-are-clickable) are buttons, that is, `<gl-button icon="close" />` is used and not `<gl-icon />`.
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- Icon-only buttons have an `aria-label`.
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- Interactive elements can be [accessed with the Tab key](#support-keyboard-only-use) and have a visible focus state.
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- Elements with [tooltips](https://design.gitlab.com/components/tooltip#accessibility) are focusable using the Tab key.
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- Are any `role`, `tabindex` or `aria-*` attributes unnecessary?
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- Can any `div` or `span` elements be replaced with a more semantic [HTML element](https://developer.mozilla.org/en-US/docs/Web/HTML/Element) like `p`, `button`, or `time`?
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## Provide a good document outline
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[Headings are the primary mechanism used by screen reader users to navigate content](https://webaim.org/projects/screenreadersurvey8/#finding).
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Therefore, the structure of headings on a page should make sense, like a good table of contents.
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We should ensure that:
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- There is only one `h1` element on the page.
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- Heading levels are not skipped.
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- Heading levels are nested correctly.
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## Provide accessible names for screen readers
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To provide markup with accessible names, ensure every:
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- input has an [associated `label`](#examples-of-providing-accessible-names).
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- button and link have [visible text](#buttons-and-links-with-descriptive-accessible-names), or `aria-label` when there is no visible text, such as for an icon button with no content.
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- image has an [`alt` attribute](#images-with-accessible-names).
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- [chart has a long and short description](https://www.w3.org/WAI/tutorials/images/complex/).
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- `fieldset` has `legend` as its first child.
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- `figure` has `figcaption` as its first child.
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- `table` has `caption` as its first child.
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Remember that an [`alt` attribute](#images-with-accessible-names) should not be longer than approximately 150 characters. While there's no official guidelines on the length, some screen readers will not read longer strings inside the `alt` attribute.
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An accessible name can be provided in multiple ways and is decided with [accessible name calculation](https://www.w3.org/WAI/ARIA/apg/practices/names-and-descriptions/#name_calculation). Here is the simplified order of different techniques taking precedence:
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1. `aria-labelledby`
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1. `aria-label`
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1. `alt`, `legend`, `figcaption` or `caption`
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1. `title`.
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### Examples of providing accessible names
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The following subsections contain examples of markup that render HTML elements with accessible names.
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Note that [when using `GlFormGroup`](https://bootstrap-vue.org/docs/components/form-group#accessibility):
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- Passing only a `label` prop renders a `fieldset` with a `legend` containing the `label` value.
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- Passing both a `label` and a `label-for` prop renders a `label` that points to the form input with the same `label-for` ID.
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#### Form inputs with accessible names
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Groups of checkboxes and radio inputs should be grouped together in a `fieldset` with a `legend`.
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`legend` gives the group of checkboxes and radio inputs a label.
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If the `label`, child text, or child element is not visually desired,
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use the class name `gl-sr-only` to hide the element from everything but screen readers.
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File input examples:
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```html
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<!-- File input with a label -->
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<label for="attach-file">{{ __('Attach a file') }}</label>
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<input id="attach-file" type="file" />
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<!-- File input with a hidden label -->
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<label for="attach-file" class="gl-sr-only">{{ __('Attach a file') }}</label>
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<input id="attach-file" type="file" />
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```
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#### Images with accessible names
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Image examples:
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```html
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<img :src="imagePath" :alt="__('A description of the image')" />
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<!-- SVGs implicitly have a graphics role so if it is semantically an image we should apply `role="img"` -->
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<svg role="img" :alt="__('A description of the image')" />
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<!-- A decorative image, hidden from screen readers -->
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<img :src="imagePath" :alt="" />
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```
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#### Buttons and links with descriptive accessible names
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Buttons and links should have accessible names that are descriptive enough to be understood in isolation.
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```html
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<!-- bad -->
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<gl-button @click="handleClick">{{ __('Submit') }}</gl-button>
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<gl-link :href="url">{{ __('page') }}</gl-link>
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<!-- good -->
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<gl-button @click="handleClick">{{ __('Submit review') }}</gl-button>
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<gl-link :href="url">{{ __("GitLab's accessibility page") }}</gl-link>
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```
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## Role
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In general, avoid using `role`.
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Use semantic HTML elements that implicitly have a `role` instead.
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| Bad | Good |
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| --- | --- |
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| `<div role="button">` | `<button>` |
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| `<div role="img">` | `<img>` |
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| `<div role="link">` | `<a>` |
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| `<div role="header">` | `<h1>` to `<h6>` |
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| `<div role="textbox">` | `<input>` or `<textarea>` |
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| `<div role="article">` | `<article>` |
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| `<div role="list">` | `<ol>` or `<ul>` |
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| `<div role="listitem">` | `<li>` |
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| `<div role="table">` | `<table>` |
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| `<div role="rowgroup">` | `<thead>`, `<tbody>`, or `<tfoot>` |
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| `<div role="row">` | `<tr>` |
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| `<div role="columnheader">` | `<th>` |
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| `<div role="cell">` | `<td>` |
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## Support keyboard-only use
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Keyboard users rely on focus outlines to understand where they are on the page. Therefore, if an
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element is interactive you must ensure:
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- It can receive keyboard focus.
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- It has a visible focus state.
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Use semantic HTML, such as `a` (`GlLink`) and `button` (`GlButton`), which provides these behaviours by default.
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Keep in mind that:
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- <kbd>Tab</kbd> and <kbd>Shift-Tab</kbd> should only move between interactive elements, not static content.
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- When you add `:hover` styles, in most cases you should add `:focus` styles too so that the styling is applied for both mouse **and** keyboard users.
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- If you remove an interactive element's `outline`, make sure you maintain visual focus state in another way such as with `box-shadow`.
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See the [Pajamas Keyboard-only page](https://design.gitlab.com/accessibility/keyboard-only) for more detail.
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## `tabindex`
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Prefer **no** `tabindex` to using `tabindex`, since:
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- Using semantic HTML such as `button` (`GlButton`) implicitly provides `tabindex="0"`.
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- Tabbing order should match the visual reading order and positive `tabindex`s interfere with this.
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### Avoid using `tabindex="0"` to make an element interactive
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Use interactive elements instead of `div` and `span` tags.
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For example:
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- If the element should be clickable, use a `button` (`GlButton`).
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- If the element should be text editable, use an [`input`](https://design.gitlab.com/components/text-input#accessibility) or [`textarea`](https://design.gitlab.com/components/textarea#accessibility).
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Once the markup is semantically complete, use CSS to update it to its desired visual state.
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```html
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<!-- bad -->
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<div role="button" tabindex="0" @click="expand">Expand</div>
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<!-- good -->
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<gl-button class="gl-p-0!" category="tertiary" @click="expand">Expand</gl-button>
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```
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### Do not use `tabindex="0"` on interactive elements
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Interactive elements are already tab accessible so adding `tabindex` is redundant.
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```html
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<!-- bad -->
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<gl-link href="help" tabindex="0">Help</gl-link>
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<gl-button tabindex="0">Submit</gl-button>
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<!-- good -->
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<gl-link href="help">Help</gl-link>
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<gl-button>Submit</gl-button>
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```
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### Do not use `tabindex="0"` on elements for screen readers to read
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Screen readers can read text that is not tab accessible.
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The use of `tabindex="0"` is unnecessary and can cause problems,
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as screen reader users then expect to be able to interact with it.
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```html
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<!-- bad -->
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<p tabindex="0" :aria-label="message">{{ message }}</p>
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<!-- good -->
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<p>{{ message }}</p>
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```
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### Do not use a positive `tabindex`
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[Always avoid using `tabindex="1"`](https://webaim.org/techniques/keyboard/tabindex#overview)
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or greater.
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## Icons
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Icons can be split into three different types:
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- Icons that are decorative
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- Icons that convey meaning
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- Icons that are clickable
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### Icons that are decorative
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Icons are decorative when there's no loss of information to the user when they are removed from the UI.
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As the majority of icons within GitLab are decorative, `GlIcon` automatically hides its rendered icons from screen readers.
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Therefore, you do not need to add `aria-hidden="true"` to `GlIcon`, as this is redundant.
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```html
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<!-- unnecessary: gl-icon hides icons from screen readers by default -->
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<gl-icon name="rocket" aria-hidden="true" />
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<!-- good -->
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<gl-icon name="rocket" />
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```
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### Icons that convey information
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Icons convey information if there is loss of information to the user when they are removed from the UI.
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An example is a confidential icon that conveys the issue is confidential, and does not have the text "Confidential" next to it.
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Icons that convey information must have an accessible name so that the information is conveyed to screen reader users too.
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```html
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<!-- bad -->
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<gl-icon name="eye-slash" />
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<!-- good -->
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<gl-icon name="eye-slash" :aria-label="__('Confidential issue')" />
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```
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### Icons that are clickable
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Icons that are clickable are semantically buttons, so they should be rendered as buttons, with an accessible name.
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```html
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<!-- bad -->
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<gl-icon name="close" :aria-label="__('Close')" @click="handleClick" />
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<!-- good -->
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<gl-button icon="close" category="tertiary" :aria-label="__('Close')" @click="handleClick" />
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```
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## Hiding elements
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Use the following table to hide elements from users, when appropriate.
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| Hide from sighted users | Hide from screen readers | Hide from both sighted and screen reader users |
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| --- | --- | --- |
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| `.gl-sr-only` | `aria-hidden="true"` | `display: none`, `visibility: hidden`, or `hidden` attribute |
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### Hide decorative images from screen readers
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To reduce noise for screen reader users, hide decorative images using `alt=""`.
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If the image is not an `img` element, such as an inline SVG, you can hide it by adding both `role="img"` and `alt=""`.
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`gl-icon` components automatically hide their icons from screen readers so `aria-hidden="true"` is
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unnecessary when using `gl-icon`.
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```html
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<!-- good - decorative images hidden from screen readers -->
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<img src="decorative.jpg" alt="">
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<svg role="img" alt="" />
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<gl-icon name="epic" />
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```
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## When to use ARIA
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No ARIA is required when using semantic HTML, because it already incorporates accessibility.
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However, there are some UI patterns that do not have semantic HTML equivalents.
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General examples of these are dialogs (modals) and tabs.
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GitLab-specific examples are assignee and label dropdowns.
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Building such widgets require ARIA to make them understandable to screen readers.
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Proper research and testing should be done to ensure compliance with [WCAG](https://www.w3.org/WAI/standards-guidelines/wcag/).
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