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Update accessibility guidelines

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doc/development/fe_guide/accessibility.md
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......@@ -15,39 +15,264 @@ This page contains guidelines we should follow.
Since [no ARIA is better than bad ARIA](https://www.w3.org/TR/wai-aria-practices/#no_aria_better_bad_aria),
review the following recommendations before using `aria-*`, `role`, and `tabindex`.
Use semantic HTML, which typically has accessibility semantics baked in, but always be sure to test with
Use semantic HTML, which has accessibility semantics baked in, and ideally test with
[relevant combinations of screen readers and browsers](https://www.accessibility-developer-guide.com/knowledge/screen-readers/relevant-combinations/).
In [WebAIM's accessibility analysis of the top million home pages](https://webaim.org/projects/million/#aria),
they found that "ARIA correlated to higher detectable errors".
It is likely that *misuse* of ARIA is a big cause of increased errors,
so when in doubt don't use `aria-*`, `role`, and `tabindex`, and stick with semantic HTML.
## Provide accessible names to screen readers
so when in doubt don't use `aria-*`, `role`, and `tabindex` and stick with semantic HTML.
## Quick checklist
- [Text](#text-inputs-with-accessible-names),
[select](#select-inputs-with-accessible-names),
[checkbox](#checkbox-inputs-with-accessible-names),
[radio](#radio-inputs-with-accessible-names),
[file](#file-inputs-with-accessible-names),
and [toggle](#gltoggle-components-with-an-accessible-names) inputs have accessible names.
- [Buttons](#buttons-and-links-with-descriptive-accessible-names),
[links](#buttons-and-links-with-descriptive-accessible-names),
and [images](#images-with-accessible-names) have descriptive accessible names.
- Icons
- [Non-decorative icons](#icons-that-convey-information) have an `aria-label`.
- [Clickable icons](#icons-that-are-clickable) are buttons, that is, `<gl-button icon="close" />` is used and not `<gl-icon />`.
- Icon-only buttons have an `aria-label`.
- Interactive elements can be [accessed with the Tab key](#support-keyboard-only-use) and have a visible focus state.
- Are any `role`, `tabindex` or `aria-*` attributes unnecessary?
- 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`?
## Provide accessible names for screen readers
To provide markup with accessible names, ensure every:
- `input` has an associated `label`.
- `button` and `a` have child text, or `aria-label` when text isn't present.
For example, an icon button with no visible text.
- `button` and `a` have child text, or `aria-label` when child text isn't present, such as for an icon button with no content.
- `img` has an `alt` attribute.
- `fieldset` has `legend` as its first child.
- `figure` has `figcaption` as its first child.
- `table` has `caption` as its first child.
Groups of checkboxes and radio inputs should be grouped together in a `fieldset` with a `legend`.
`legend` gives the group of checkboxes and radio inputs a label.
If the `label`, child text, or child element is not visually desired,
use `.gl-sr-only` to hide the element from everything but screen readers.
Ensure the accessible name is descriptive enough to be understood in isolation.
### Examples of providing accessible names
The following subsections contain examples of markup that render HTML elements with accessible names.
Note that [when using `GlFormGroup`](https://bootstrap-vue.org/docs/components/form-group#accessibility):
- Passing only a `label` prop renders a `fieldset` with a `legend` containing the `label` value.
- Passing both a `label` and a `label-for` prop renders a `label` that points to the form input with the same `label-for` ID.
#### Text inputs with accessible names
When using `GlFormGroup`, the `label` prop alone does not give the input an accessible name.
The `label-for` prop must also be provided to give the input an accessible name.
Text input examples:
```html
<!-- Input with label -->
<gl-form-group :label="__('Issue title')" label-for="issue-title">
<gl-form-input id="issue-title" v-model="title" name="title" />
</gl-form-group>
<!-- Input with hidden label -->
<gl-form-group :label="__('Issue title')" label-for="issue-title" :label-sr-only="true">
<gl-form-input id="issue-title" v-model="title" name="title" />
</gl-form-group>
```
Textarea examples:
```html
<!-- Textarea with label -->
<gl-form-group :label="__('Issue description')" label-for="issue-description">
<gl-form-textarea id="issue-description" v-model="description" name="description" />
</gl-form-group>
<!-- Textarea with hidden label -->
<gl-form-group :label="__('Issue description')" label-for="issue-description" :label-sr-only="true">
<gl-form-textarea id="issue-description" v-model="description" name="description" />
</gl-form-group>
```
Alternatively, you can use a plain `label` element:
```html
<!-- Input with label using `label` -->
<label for="issue-title">{{ __('Issue title') }}</label>
<gl-form-input id="issue-title" v-model="title" name="title" />
<!-- Input with hidden label using `label` -->
<label for="issue-title" class="gl-sr-only">{{ __('Issue title') }}</label>
<gl-form-input id="issue-title" v-model="title" name="title" />
```
#### Select inputs with accessible names
Select input examples:
```html
<!-- Select input with label -->
<gl-form-group :label="__('Issue status')" label-for="issue-status">
<gl-form-select id="issue-status" v-model="status" name="status" :options="options" />
</gl-form-group>
<!-- Select input with hidden label -->
<gl-form-group :label="__('Issue status')" label-for="issue-status" :label-sr-only="true">
<gl-form-select id="issue-status" v-model="status" name="status" :options="options" />
</gl-form-group>
```
#### Checkbox inputs with accessible names
Single checkbox:
```html
<!-- Single checkbox with label -->
<gl-form-checkbox v-model="status" name="status" value="task-complete">
{{ __('Task complete') }}
</gl-form-checkbox>
<!-- Single checkbox with hidden label -->
<gl-form-checkbox v-model="status" name="status" value="task-complete">
<span class="gl-sr-only">{{ __('Task complete') }}</span>
</gl-form-checkbox>
```
Multiple checkboxes:
```html
<!-- Multiple labeled checkboxes grouped within a fieldset -->
<gl-form-group :label="__('Task list')">
<gl-form-checkbox name="task-list" value="task-1">{{ __('Task 1') }}</gl-form-checkbox>
<gl-form-checkbox name="task-list" value="task-2">{{ __('Task 2') }}</gl-form-checkbox>
</gl-form-group>
<!-- Or -->
<gl-form-group :label="__('Task list')">
<gl-form-checkbox-group v-model="selected" :options="options" name="task-list" />
</gl-form-group>
<!-- Multiple labeled checkboxes grouped within a fieldset with hidden legend -->
<gl-form-group :label="__('Task list')" :label-sr-only="true">
<gl-form-checkbox name="task-list" value="task-1">{{ __('Task 1') }}</gl-form-checkbox>
<gl-form-checkbox name="task-list" value="task-2">{{ __('Task 2') }}</gl-form-checkbox>
</gl-form-group>
<!-- Or -->
<gl-form-group :label="__('Task list')" :label-sr-only="true">
<gl-form-checkbox-group v-model="selected" :options="options" name="task-list" />
</gl-form-group>
```
#### Radio inputs with accessible names
Single radio input:
```html
<!-- Single radio with a label -->
<gl-form-radio v-model="status" name="status" value="opened">
{{ __('Opened') }}
</gl-form-radio>
<!-- Single radio with a hidden label -->
<gl-form-radio v-model="status" name="status" value="opened">
<span class="gl-sr-only">{{ __('Opened') }}</span>
</gl-form-radio>
```
Multiple radio inputs:
```html
<!-- Multiple labeled radio inputs grouped within a fieldset -->
<gl-form-group :label="__('Issue status')">
<gl-form-radio name="status" value="opened">{{ __('Opened') }}</gl-form-radio>
<gl-form-radio name="status" value="closed">{{ __('Closed') }}</gl-form-radio>
</gl-form-group>
<!-- Or -->
<gl-form-group :label="__('Issue status')">
<gl-form-radio-group v-model="selected" :options="options" name="status" />
</gl-form-group>
<!-- Multiple labeled radio inputs grouped within a fieldset with hidden legend -->
<gl-form-group :label="__('Issue status')" :label-sr-only="true">
<gl-form-radio name="status" value="opened">{{ __('Opened') }}</gl-form-radio>
<gl-form-radio name="status" value="closed">{{ __('Closed') }}</gl-form-radio>
</gl-form-group>
<!-- Or -->
<gl-form-group :label="__('Issue status')" :label-sr-only="true">
<gl-form-radio-group v-model="selected" :options="options" name="status" />
</gl-form-group>
```
#### File inputs with accessible names
File input examples:
```html
<!-- File input with a label -->
<label for="attach-file">{{ __('Attach a file') }}</label>
<input id="attach-file" type="file" name="attach-file" />
<!-- File input with a hidden label -->
<label for="attach-file" class="gl-sr-only">{{ __('Attach a file') }}</label>
<input id="attach-file" type="file" name="attach-file" />
```
#### GlToggle components with an accessible names
`GlToggle` examples:
```html
// bad
<button>Submit</button>
<a href="url">page</a>
<!-- GlToggle with label -->
<gl-toggle v-model="notifications" :label="__('Notifications')" />
// good
<button>Submit review</button>
<a href="url">GitLab's accessibility page</a>
<!-- GlToggle with hidden label -->
<gl-toggle v-model="notifications" :label="__('Notifications')" label-position="hidden" />
```
#### GlFormCombobox components with an accessible names
`GlFormCombobox` examples:
```html
<!-- GlFormCombobox with label -->
<gl-form-combobox :label-text="__('Key')" :token-list="$options.tokenList" />
```
#### Images with accessible names
Image examples:
```html
<img :src="imagePath" :alt="__('A description of the image')" />
<!-- SVGs implicitly have a graphics role so if it is semantically an image we should apply `role="img"` -->
<svg role="img" :alt="__('A description of the image')" />
```
#### Buttons and links with descriptive accessible names
Buttons and links should have accessible names that are descriptive enough to be understood in isolation.
```html
<!-- bad -->
<gl-button @click="handleClick">{{ __('Submit') }}</gl-button>
<gl-link :href="url">{{ __('page') }}</gl-link>
<!-- good -->
<gl-button @click="handleClick">{{ __('Submit review') }}</gl-button>
<gl-link :href="url">{{ __("GitLab's accessibility page") }}</gl-link>
```
## Role
......@@ -81,31 +306,37 @@ element is interactive you must ensure:
Use semantic HTML, such as `a` and `button`, which provides these behaviours by default.
Keep in mind that:
- <kbd>Tab</kbd> and <kbd>Shift-Tab</kbd> should only move between interactive elements, not static content.
- 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.
- If you remove an interactive element's `outline`, make sure you maintain visual focus state in another way such as with `box-shadow`.
See the [Pajamas Keyboard-only page](https://design.gitlab.com/accessibility-audits/2-keyboard-only/) for more detail.
## Tabindex
Prefer **no** `tabindex` to using `tabindex`, since:
- Using semantic HTML such as `button` implicitly provides `tabindex="0"`
- Tabbing order should match the visual reading order and positive `tabindex`s interfere with this
- Using semantic HTML such as `button` implicitly provides `tabindex="0"`.
- Tabbing order should match the visual reading order and positive `tabindex`s interfere with this.
### Avoid using `tabindex="0"` to make an element interactive
Use interactive elements instead of `div`s and `span`s.
Use interactive elements instead of `div` and `span` tags.
For example:
- If the element should be clickable, use a `button`
- If the element should be text editable, use an `input` or `textarea`
- If the element should be clickable, use a `button`.
- If the element should be text editable, use an `input` or `textarea`.
Once the markup is semantically complete, use CSS to update it to its desired visual state.
```html
// bad
<!-- bad -->
<div role="button" tabindex="0" @click="expand">Expand</div>
// good
<button @click="expand">Expand</button>
<!-- good -->
<gl-button @click="expand">Expand</gl-button>
```
### Do not use `tabindex="0"` on interactive elements
......@@ -113,13 +344,13 @@ Once the markup is semantically complete, use CSS to update it to its desired vi
Interactive elements are already tab accessible so adding `tabindex` is redundant.
```html
// bad
<a href="help" tabindex="0">Help</a>
<button tabindex="0">Submit</button>
<!-- bad -->
<gl-link href="help" tabindex="0">Help</gl-link>
<gl-button tabindex="0">Submit</gl-button>
// good
<a href="help">Help</a>
<button>Submit</button>
<!-- good -->
<gl-link href="help">Help</gl-link>
<gl-button>Submit</gl-button>
```
### Do not use `tabindex="0"` on elements for screen readers to read
......@@ -129,10 +360,10 @@ The use of `tabindex="0"` is unnecessary and can cause problems,
as screen reader users then expect to be able to interact with it.
```html
// bad
<span tabindex="0" :aria-label="message">{{ message }}</span>
<!-- bad -->
<p tabindex="0" :aria-label="message">{{ message }}</p>
// good
<!-- good -->
<p>{{ message }}</p>
```
......@@ -141,6 +372,57 @@ as screen reader users then expect to be able to interact with it.
[Always avoid using `tabindex="1"`](https://webaim.org/techniques/keyboard/tabindex#overview)
or greater.
## Icons
Icons can be split into three different types:
- Icons that are decorative
- Icons that convey meaning
- Icons that are clickable
### Icons that are decorative
Icons are decorative when there's no loss of information to the user when they are removed from the UI.
As the majority of icons within GitLab are decorative, `GlIcon` automatically hides its rendered icons from screen readers.
Therefore, you do not need to add `aria-hidden="true"` to `GlIcon`, as this is redundant.
```html
<!-- unnecessary — gl-icon hides icons from screen readers by default -->
<gl-icon name="rocket" aria-hidden="true" />`
<!-- good -->
<gl-icon name="rocket" />`
```
### Icons that convey information
Icons convey information if there is loss of information to the user when they are removed from the UI.
An example is a confidential icon that conveys the issue is confidential, and does not have the text "Confidential" next to it.
Icons that convey information must have an accessible name so that the information is conveyed to screen reader users too.
```html
<!-- bad -->
<gl-icon name="eye-slash" />`
<!-- good -->
<gl-icon name="eye-slash" :aria-label="__('Confidential issue')" />`
```
### Icons that are clickable
Icons that are clickable are semantically buttons, so they should be rendered as buttons, with an accessible name.
```html
<!-- bad -->
<gl-icon name="close" :aria-label="__('Close')" @click="handleClick" />
<!-- good -->
<gl-button icon="close" category="tertiary" :aria-label="__('Close')" @click="handleClick" />
```
## Hiding elements
Use the following table to hide elements from users, when appropriate.
......@@ -158,22 +440,24 @@ If the image is not an `img` element, such as an inline SVG, you can hide it by
unnecessary when using `gl-icon`.
```html
// good - decorative images hidden from screen readers
<!-- good - decorative images hidden from screen readers -->
<img src="decorative.jpg" alt="">
<svg role="img" alt="">
<gl-icon name="epic"/>
<svg role="img" alt="" />
<gl-icon name="epic" />
```
## When should ARIA be used
## When to use ARIA
No ARIA is required when using semantic HTML because it incorporates accessibility.
No ARIA is required when using semantic HTML, because it already incorporates accessibility.
However, there are some UI patterns and widgets that do not have semantic HTML equivalents.
However, there are some UI patterns that do not have semantic HTML equivalents.
General examples of these are dialogs (modals) and tabs.
GitLab-specific examples are assignee and label dropdowns.
Building such widgets require ARIA to make them understandable to screen readers.
Proper research and testing should be done to ensure compliance with ARIA.
Ideally, these widgets would exist only in [GitLab UI](https://gitlab-org.gitlab.io/gitlab-ui/).
Use of ARIA would then only occur in [GitLab UI](https://gitlab.com/gitlab-org/gitlab-ui/) and not [GitLab](https://gitlab.com/gitlab-org/gitlab/).
Proper research and testing should be done to ensure compliance with [WCAG](https://www.w3.org/WAI/standards-guidelines/wcag/).
## Resources
......
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