What does the component do?
A checkbox is a selection field that allows users to select or deselect one or more options from a list.
When should the component be used?
- To allow users to select multiple independent options.
- To offer a yes/no or on/off selection.
- To confirm consents or conditions (e.g. newsletter subscription).
Rules
- Each checkbox should be clearly labelled and name the option unambiguously.
- Groups of checkboxes should be logically organised.
- Avoid too many options in a group in order to maintain clarity (max. 5-7 options).
| Number | Type | Description | Optional | Info |
|---|---|---|---|---|
| 1 | Text | Label | No |
Playground
The sbb-checkbox component provides the same functionality as a native <input type="checkbox"/> enhanced with the SBB Design.
Slots
It is possible to provide a label via an unnamed slot; the component can optionally display a sbb-icon using
the iconName property or via custom SVG using the icon slot.
The icon can be placed before or after the label based on the value of the iconPlacement property (default: end).
<sbb-checkbox value="checkbox">Example</sbb-checkbox>
<sbb-checkbox value="icon" icon-name="tickets-class-small">Icon</sbb-checkbox>
<sbb-checkbox value="start-icon" icon-name="tickets-class-small" icon-placement="start"
>Icon at start</sbb-checkbox
>
States
The component could be checked or not depending on the value of the checked attribute.
<sbb-checkbox value="checked-checkbox" checked>Checked state</sbb-checkbox>
It has a third state too, which is set if the indeterminate property is true.
This is useful when multiple dependent checkboxes are used
(e.g., a parent which is checked only if all the children are checked, otherwise is in indeterminate state).
Clicking on a sbb-checkbox in this state sets checked to true and indeterminate to false.
<sbb-checkbox value="indeterminate-checkbox" indeterminate="true">Indeterminate state</sbb-checkbox>
The component can be displayed in disabled or required state by using the self-named properties.
<sbb-checkbox value="required-checkbox" required="true">Required</sbb-checkbox>
<sbb-checkbox value="disabled-checkbox" disabled="true">Disabled</sbb-checkbox>
Style
The component has three possible size values, named xs, s and m (default).
<sbb-checkbox value="size" size="xs">Size</sbb-checkbox>
<sbb-checkbox value="size" size="s">Size</sbb-checkbox>
The component's label can be displayed in bold using the sbb-text--bold class on a wrapper tag:
<sbb-checkbox value="bold">
<span class="sbb-text--bold">Bold label</span>
</sbb-checkbox>
Events
Consumers can listen to the native change event on the sbb-checkbox component to intercept the input's change;
the current state can be read from event.target.checked, while the value from event.target.value.
Accessibility
The component provides the same accessibility features as the native checkbox.
Avoid adding other interactive controls into the content of sbb-checkbox, as this degrades the experience for users of assistive technology.
Always provide an accessible label via aria-label for checkboxes without descriptive text content.
If you don't want the label to appear next to the checkbox, you can use aria-label to specify an appropriate label.
<sbb-checkbox aria-label="Subscribed to email message"></sbb-checkbox>
Complex Values
This component supports any types of values, including complex objects.
The type can be specified using the generic type parameter T of SbbCheckbox<T>.
<sbb-checkbox .value=${{value: 'value', name: 'name'}} name="name">Checkbox</sbb-checkbox>
Properties
| Name | Attribute | Privacy | Type | Default | Description |
|---|---|---|---|---|---|
checked | checked | public | boolean | false | Whether the checkbox is checked. |
disabled | disabled | public | boolean | false | Whether the component is disabled. |
form | - | public | HTMLFormElement | null | Returns the form owner of this element. | |
group | - | public | SbbCheckboxGroupElement | null | null | Reference to the connected checkbox group. |
iconName | icon-name | public | string | '' | The icon name we want to use, choose from the small icon variants from the ui-icons category from here https://icons.app.sbb.ch. |
iconPlacement | icon-placement | public | SbbIconPlacement | 'end' | The label position relative to the labelIcon. Defaults to end |
indeterminate | indeterminate | public | boolean | false | Whether the checkbox is indeterminate. |
name | name | public | string | Name of the form element. Will be read from name attribute. | |
required | required | public | boolean | false | Whether the component is required. |
size | size | public | SbbCheckboxSize | 'm' / 'xs' (lean) | Size variant, either xs, s or m. |
type | - | public | string | 'checkbox' | Form type of element. |
validationMessage | - | public | string | Returns the current error message, if available, which corresponds to the current validation state. Please note that only one message is returned at a time (e.g. if multiple validity states are invalid, only the chronologically first one is returned until it is fixed, at which point the next message might be returned, if it is still applicable). Also, a custom validity message (see below) has precedence over native validation messages. | |
validity | - | public | ValidityState | Returns the ValidityState object for this element. | |
value | value | public | (T = string) | null | null | Value of the form element. |
willValidate | - | public | boolean | Returns true if this element will be validated when the form is submitted; false otherwise. |
Methods
| Name | Privacy | Description | Parameters | Return | Inherited From |
|---|---|---|---|---|---|
checkValidity | public | Returns true if this element has no validity problems; false otherwise. Fires an invalid event at the element in the latter case. | boolean | SbbFormAssociatedMixin | |
reportValidity | public | Returns true if this element has no validity problems; otherwise, returns false, fires an invalid event at the element, and (if the event isn't canceled) reports the problem to the user. | boolean | SbbFormAssociatedMixin | |
setCustomValidity | public | Sets the custom validity message for this element. Use the empty string to indicate that the element does not have a custom validity error. | message: string | void | SbbFormAssociatedMixin |
Events
| Name | Type | Description | Inherited From |
|---|---|---|---|
change | Event | The change event is fired when the user modifies the element's value. Unlike the input event, the change event is not necessarily fired for each alteration to an element's value. | |
input | InputEvent | The input event fires when the value has been changed as a direct result of a user action. |
Slots
| Name | Description |
|---|---|
Use the unnamed slot to add content to the sbb-checkbox. | |
icon | Slot used to render the checkbox icon (disabled inside a selection panel). |