Enables users to choose from a list of options presented in a dropdown.
Overview
The Select component provides users with a selectable list of options. It's designed to offer an enhanced selection experience with features like typeahead search, keyboard navigation, and customizable grouping. This component is particularly useful for scenarios where users need to choose from a predefined set of options, offering more functionality than a standard select element.
Key Features
Typeahead Search: Users can quickly find options by typing
Keyboard Navigation: Full support for keyboard interactions, allowing users to navigate through options using arrow keys, enter to select, and more.
Grouped Options: Ability to organize options into logical groups, enhancing readability and organization of large option sets.
Scroll Management: Includes scroll up/down buttons for easy navigation in long lists.
Accessibility: Built-in ARIA attributes and keyboard support ensure compatibility with screen readers and adherence to accessibility standards.
Portal Support: Option to render the select content in a portal, preventing layout issues in complex UI structures.
Architecture
The Select component is composed of several sub-components, each with a specific role:
Root: The main container component that manages the state and context for the combobox.
Trigger: The button or element that opens the dropdown list.
Portal: Responsible for portalling the dropdown content to the body or a custom target.
Group: A container for grouped items, used to group related items.
GroupHeading: A heading for a group of items, providing a descriptive label for the group.
Item: An individual item within the list.
Separator: A visual separator between items.
Content: The dropdown container that displays the items. It uses Floating UI to position the content relative to the trigger.
ContentStatic (Optional): An alternative to the Content component, that enables you to opt-out of Floating UI and position the content yourself.
Arrow: An arrow element that points to the trigger when using the Combobox.Content component.
Structure
Here's an overview of how the Select component is structured in code:
Reusable Components
As you can see from the structure above, there are a number of pieces that make up the Select component. These pieces are provided to give you maximum flexibility and customization options, but can be a burden to write out everywhere you need to use a select in your application.
To ease this burden, it's recommended to create your own reusable select component that wraps the primitives and provides a more convenient API for your use cases.
Here's an example of how you might create a reusable MySelect component that receives a list of options and renders each of them as an item.
You can then use the MySelect component throughout your application like so:
Managing Value State
Bits UI offers several approaches to manage and synchronize the Select's value state, catering to different levels of control and integration needs.
1. Two-Way Binding
For seamless state synchronization, use Svelte's bind:value directive. This method automatically keeps your local state in sync with the component's internal state.
Key Benefits
Simplifies state management
Automatically updates myValue when the internal state changes (e.g., via clicking on an item)
Allows external control (e.g., selecting an item via a separate button)
2. Change Handler
For more granular control or to perform additional logic on state changes, use the onValueChange prop. This approach is useful when you need to execute custom logic alongside state updates.
Use Cases
Implementing custom behaviors on value change
Integrating with external state management solutions
Triggering side effects (e.g., logging, data fetching)
3. Fully Controlled
For complete control over the component's value state, use the controlledValue prop. This approach requires you to manually manage the value state, giving you full control over when and how the component responds to value change events.
To implement controlled state:
Set the controlledValue prop to true on the Select.Root component.
Provide a value prop to Select.Root, which should be a variable holding the current state.
Implement an onValueChange handler to update the state when the internal state changes.
When to Use
Implementing complex open/close logic
Coordinating multiple UI elements
Debugging state-related issues
Note
While powerful, fully controlled state should be used judiciously as it increases complexity and can cause unexpected behaviors if not handled carefully.
For more in-depth information on controlled components and advanced state management techniques, refer to our Controlled State documentation.
Managing Open State
Bits UI offers several approaches to manage and synchronize the Select's open state, catering to different levels of control and integration needs.
1. Two-Way Binding
For seamless state synchronization, use Svelte's bind:open directive. This method automatically keeps your local state in sync with the component's internal state.
Key Benefits
Simplifies state management
Automatically updates myOpen when the internal state changes (e.g., via clicking on the trigger/input)
Allows external control (e.g., opening via a separate button)
2. Change Handler
For more granular control or to perform additional logic on state changes, use the onOpenChange prop. This approach is useful when you need to execute custom logic alongside state updates.
Use Cases
Implementing custom behaviors on open change
Integrating with external state management solutions
Triggering side effects (e.g., logging, data fetching)
3. Fully Controlled
For complete control over the component's value state, use the controlledOpen prop. This approach requires you to manually manage the value state, giving you full control over when and how the component responds to value change events.
To implement controlled state:
Set the controlledOpen prop to true on the Select.Root component.
Provide an open prop to Select.Root, which should be a variable holding the current state.
Implement an onOpenChange handler to update the state when the internal state changes.
When to Use
Implementing complex open/close logic
Coordinating multiple UI elements
Debugging state-related issues
Note
While powerful, fully controlled state should be used judiciously as it increases complexity and can cause unexpected behaviors if not handled carefully.
For more in-depth information on controlled components and advanced state management techniques, refer to our Controlled State documentation.
Multiple Selection
The type prop can be set to 'multiple' to allow multiple items to be selected at a time.
Opt-out of Floating UI
When you use the Select.Content component, Bits UI uses Floating UI to position the content relative to the trigger, similar to other popover-like components.
You can opt-out of this behavior by instead using the Select.ContentStatic component.
When using this component, you'll need to handle the positioning of the content yourself. Keep in mind that using Select.Portal alongside Select.ContentStatic may result in some unexpected positioning behavior, feel free to not use the portal or work around it.
Custom Anchor
By default, the Select.Content is anchored to the Select.Trigger component, which determines where the content is positioned.
If you wish to instead anchor the content to a different element, you can pass either a selector string or an HTMLElement to the customAnchor prop of the Select.Content component.
Custom Anchor
What is the Viewport?
The Select.Viewport component is used to determine the size of the content in order to determine whether or not the scroll up and down buttons should be rendered.
If you wish to set a minimum/maximum height for the select content, you should apply it to the Select.Viewport component.
Scroll Up/Down Buttons
The Select.ScrollUpButton and Select.ScrollDownButton components are used to render the scroll up and down buttons when the select content is larger than the viewport.
You must use the Select.Viewport component when using the scroll buttons.
Native Scrolling/Overflow
If you don't want to use the scroll buttons and prefer to use the standard scrollbar/overflow behavior, you can omit the Select.Scroll[Up|Down]Button components and the Select.Viewport component.
You'll need to set a height on the Select.Content component and appropriate overflow styles to enable scrolling.
Scroll Lock
By default, when a user opens the select, scrolling outside the content will not be disabled. You can override this behavior by setting the preventScroll prop to true.
Highlighted Items
The Select component follows the WAI-ARIA descendant pattern for highlighting items. This means that the Select.Trigger retains focus the entire time, even when navigating with the keyboard, and items are highlighted as the user navigates them.
Styling Highlighted Items
You can use the data-highlighted attribute on the Select.Item component to style the item differently when it is highlighted.
onHighlight / onUnhighlight
To trigger side effects when an item is highlighted or unhighlighted, you can use the onHighlight and onUnhighlight props.
Svelte Transitions
You can use the forceMount prop along with the child snippet to forcefully mount the Select.Content component to use Svelte Transitions or another animation library that requires more control.
Of course, this isn't the prettiest syntax, so it's recommended to create your own reusable content component that handles this logic if you intend to use this approach. For more information on using transitions with Bits UI components, see the Transitions documentation.
API Reference
Select.Root
The root select component which manages & scopes the state of the select.
Property
Type
Description
typerequired
enum
The type of selection to use for the select.
Default: ——undefined
value$bindable
union
The value of the select. When the type is 'single', this should be a string. When the type is 'multiple', this should be an array of strings.
Default: ——undefined
onValueChange
function
A callback that is fired when the select value changes. When the type is 'single', the argument will be a string. When the type is 'multiple', the argument will be an array of strings.
Default: ——undefined
controlledValue
boolean
Whether or not the value is controlled or not. If true, the component will not update the value state internally, instead it will call onValueChange when it would have otherwise, and it is up to you to update the value prop that is passed to the component.
Default: false
open$bindable
boolean
The open state of the select menu.
Default: false
onOpenChange
function
A callback that is fired when the select menu's open state changes.
Default: ——undefined
controlledOpen
boolean
Whether or not the open state is controlled or not. If true, the component will not update the open state internally, instead it will call onOpenChange when it would have otherwise, and it is up to you to update the open prop that is passed to the component.
Default: false
disabled
boolean
Whether or not the select component is disabled.
Default: false
name
string
The name to apply to the hidden input element for form submission. If provided, a hidden input element will be rendered to submit the value of the select.
Default: ——undefined
required
boolean
Whether or not the select menu is required.
Default: false
scrollAlignment
enum
The alignment of the highlighted item when scrolling.
Default: 'nearest'
loop
boolean
Whether or not the select menu should loop through items.
Default: false
allowDeselect
boolean
Whether or not the user can deselect the selected item by pressing it in a single select.
Default: true
items
object
Optionally provide an array of value and label pairs that will be used to match and trigger selection when the trigger is focused and a key is pressed while the content is closed. Additionally, this will be used for form autofill when the type is single.
Default: ——undefined
children
Snippet
The children content to render.
Default: ——undefined
Select.Trigger
A button which toggles the select's open state.
Property
Type
Description
ref$bindable
HTMLButtonElement
The underlying DOM element being rendered. You can bind to this to get a reference to the element.
Default: ——undefined
children
Snippet
The children content to render.
Default: ——undefined
child
Snippet
Use render delegation to render your own element. See Child Snippet docs for more information.
Default: ——undefined
Data Attribute
Value
Description
data-state
enum
The select's open state.
data-placeholder
''
Present when the select does not have a value.
data-disabled
''
Present when the select is disabled.
data-select-trigger
''
Present on the trigger element.
Select.Content
The element which contains the select's items.
Property
Type
Description
side
enum
The preferred side of the anchor to render the floating element against when open. Will be reversed when collisions occur.
Default: bottom
sideOffset
number
The distance in pixels from the anchor to the floating element.
Default: 0
align
enum
The preferred alignment of the anchor to render the floating element against when open. This may change when collisions occur.
Default: start
alignOffset
number
The distance in pixels from the anchor to the floating element.
Default: 0
arrowPadding
number
The amount in pixels of virtual padding around the viewport edges to check for overflow which will cause a collision.
Default: 0
avoidCollisions
boolean
When true, overrides the side and align options to prevent collisions with the boundary edges.
Default: true
collisionBoundary
union
A boundary element or array of elements to check for collisions against.
Default: ——undefined
collisionPadding
union
The amount in pixels of virtual padding around the viewport edges to check for overflow which will cause a collision.
Default: 0
sticky
enum
The sticky behavior on the align axis. 'partial' will keep the content in the boundary as long as the trigger is at least partially in the boundary whilst 'always' will keep the content in the boundary regardless.
Default: partial
hideWhenDetached
boolean
When true, hides the content when it is detached from the DOM. This is useful for when you want to hide the content when the user scrolls away.
Default: true
updatePositionStrategy
enum
The strategy to use when updating the position of the content. When 'optimized' the content will only be repositioned when the trigger is in the viewport. When 'always' the content will be repositioned whenever the position changes.
Default: optimized
strategy
enum
The positioning strategy to use for the floating element. When 'fixed' the element will be positioned relative to the viewport. When 'absolute' the element will be positioned relative to the nearest positioned ancestor.
Default: fixed
preventScroll
boolean
When true, prevents the body from scrolling when the content is open. This is useful when you want to use the content as a modal.
Default: false
customAnchor
union
Use an element other than the trigger to anchor the content to. If provided, the content will be anchored to the provided element instead of the trigger.
Default: null
onEscapeKeydown
function
Callback fired when an escape keydown event occurs in the floating content. You can call event.preventDefault() to prevent the default behavior of handling the escape keydown event.
Default: ——undefined
escapeKeydownBehavior
enum
The behavior to use when an escape keydown event occurs in the floating content. 'close' will close the content immediately. 'ignore' will prevent the content from closing. 'defer-otherwise-close' will defer to the parent element if it exists, otherwise it will close the content. 'defer-otherwise-ignore' will defer to the parent element if it exists, otherwise it will ignore the interaction.
Default: close
onInteractOutside
function
Callback fired when an outside interaction event occurs, which is a pointerdown event. You can call event.preventDefault() to prevent the default behavior of handling the outside interaction.
Default: ——undefined
onFocusOutside
function
Callback fired when focus leaves the dismissible layer. You can call event.preventDefault() to prevent the default behavior on focus leaving the layer.
Default: ——undefined
interactOutsideBehavior
enum
The behavior to use when an interaction occurs outside of the floating content. 'close' will close the content immediately. 'ignore' will prevent the content from closing. 'defer-otherwise-close' will defer to the parent element if it exists, otherwise it will close the content. 'defer-otherwise-ignore' will defer to the parent element if it exists, otherwise it will ignore the interaction.
Default: close
onCloseAutoFocus
function
Event handler called when auto-focusing the content as it is closed. Can be prevented.
Default: ——undefined
preventOverflowTextSelection
boolean
When true, prevents the text selection from overflowing the bounds of the element.
Default: true
dir
enum
The reading direction of the app.
Default: ltr
loop
boolean
Whether or not the select should loop through items when reaching the end.
Default: false
forceMount
boolean
Whether or not to forcefully mount the content. This is useful if you want to use Svelte transitions or another animation library for the content.
Default: false
ref$bindable
HTMLDivElement
The underlying DOM element being rendered. You can bind to this to get a reference to the element.
Default: ——undefined
children
Snippet
The children content to render.
Default: ——undefined
child
Snippet
Use render delegation to render your own element. See Child Snippet docs for more information.
Default: ——undefined
Data Attribute
Value
Description
data-state
enum
The select's open state.
data-select-content
''
Present on the content element.
CSS Variable
Description
--bits-select-content-transform-origin
The transform origin of the select content element.
--bits-select-content-available-width
The available width of the select content element.
--bits-select-content-available-height
The available height of the select content element.
--bits-select-anchor-width
The width of the select trigger element.
--bits-select-anchor-height
The height of the select trigger element.
Select.ContentStatic
The element which contains the select's items. (Static/No Floating UI)
Property
Type
Description
onEscapeKeydown
function
Callback fired when an escape keydown event occurs in the floating content. You can call event.preventDefault() to prevent the default behavior of handling the escape keydown event.
Default: ——undefined
escapeKeydownBehavior
enum
The behavior to use when an escape keydown event occurs in the floating content. 'close' will close the content immediately. 'ignore' will prevent the content from closing. 'defer-otherwise-close' will defer to the parent element if it exists, otherwise it will close the content. 'defer-otherwise-ignore' will defer to the parent element if it exists, otherwise it will ignore the interaction.
Default: close
onInteractOutside
function
Callback fired when an outside interaction event occurs, which is a pointerdown event. You can call event.preventDefault() to prevent the default behavior of handling the outside interaction.
Default: ——undefined
onFocusOutside
function
Callback fired when focus leaves the dismissible layer. You can call event.preventDefault() to prevent the default behavior on focus leaving the layer.
Default: ——undefined
interactOutsideBehavior
enum
The behavior to use when an interaction occurs outside of the floating content. 'close' will close the content immediately. 'ignore' will prevent the content from closing. 'defer-otherwise-close' will defer to the parent element if it exists, otherwise it will close the content. 'defer-otherwise-ignore' will defer to the parent element if it exists, otherwise it will ignore the interaction.
Default: close
onOpenAutoFocus
function
Event handler called when auto-focusing the content as it is opened. Can be prevented.
Default: ——undefined
onCloseAutoFocus
function
Event handler called when auto-focusing the content as it is closed. Can be prevented.
Default: ——undefined
trapFocus
boolean
Whether or not to trap the focus within the content when open.
Default: true
preventScroll
boolean
When true, prevents the body from scrolling when the content is open. This is useful when you want to use the content as a modal.
Default: true
preventOverflowTextSelection
boolean
When true, prevents the text selection from overflowing the bounds of the element.
Default: true
dir
enum
The reading direction of the app.
Default: ltr
loop
boolean
Whether or not the select should loop through items when reaching the end.
Default: false
forceMount
boolean
Whether or not to forcefully mount the content. This is useful if you want to use Svelte transitions or another animation library for the content.
Default: false
ref$bindable
HTMLDivElement
The underlying DOM element being rendered. You can bind to this to get a reference to the element.
Default: ——undefined
children
Snippet
The children content to render.
Default: ——undefined
child
Snippet
Use render delegation to render your own element. See Child Snippet docs for more information.
Default: ——undefined
Data Attribute
Value
Description
data-state
enum
The select's open state.
data-select-content
''
Present on the content element.
Select.Item
A select item, which must be a child of the select.Content component.
Property
Type
Description
valuerequired
string
The value of the item.
Default: ——undefined
label
string
The label of the item, which is what the list will be filtered by using typeahead behavior.
Default: ——undefined
disabled
boolean
Whether or not the select item is disabled. This will prevent interaction/selection.
Default: false
onHighlight
function
A callback that is fired when the item is highlighted.
Default: ——undefined
onUnhighlight
function
A callback that is fired when the item is unhighlighted.
Default: ——undefined
ref$bindable
HTMLDivElement
The underlying DOM element being rendered. You can bind to this to get a reference to the element.
Default: ——undefined
children
Snippet
The children content to render.
Default: ——undefined
child
Snippet
Use render delegation to render your own element. See Child Snippet docs for more information.
Default: ——undefined
Data Attribute
Value
Description
data-value
string
The value of the select item.
data-label
string
The label of the select item.
data-disabled
''
Present when the item is disabled.
data-highlighted
''
Present when the item is highlighted, which is either via keyboard navigation of the menu or hover.
data-selected
''
Present when the item is selected.
data-select-item
''
Present on the item element.
Select.Viewport
An optional element to track the scroll position of the select for rendering the scroll up/down buttons.
Property
Type
Description
ref$bindable
HTMLDivElement
The underlying DOM element being rendered. You can bind to this to get a reference to the element.
Default: ——undefined
children
Snippet
The children content to render.
Default: ——undefined
child
Snippet
Use render delegation to render your own element. See Child Snippet docs for more information.
Default: ——undefined
Data Attribute
Value
Description
data-select-viewport
''
Present on the viewport element.
Select.ScrollUpButton
An optional scroll up button element to improve the scroll experience within the select. Should be used in conjunction with the select.Viewport component.
Property
Type
Description
ref$bindable
HTMLDivElement
The underlying DOM element being rendered. You can bind to this to get a reference to the element.
Default: ——undefined
children
Snippet
The children content to render.
Default: ——undefined
child
Snippet
Use render delegation to render your own element. See Child Snippet docs for more information.
Default: ——undefined
Data Attribute
Value
Description
data-select-scroll-up-button
''
Present on the scroll up button element.
Select.ScrollDownButton
An optional scroll down button element to improve the scroll experience within the select. Should be used in conjunction with the select.Viewport component.
Property
Type
Description
ref$bindable
HTMLDivElement
The underlying DOM element being rendered. You can bind to this to get a reference to the element.
Default: ——undefined
children
Snippet
The children content to render.
Default: ——undefined
child
Snippet
Use render delegation to render your own element. See Child Snippet docs for more information.
Default: ——undefined
Data Attribute
Value
Description
data-select-scroll-down-button
''
Present on the scroll down button element.
Select.Group
A group of related select items.
Property
Type
Description
ref$bindable
HTMLDivElement
The underlying DOM element being rendered. You can bind to this to get a reference to the element.
Default: ——undefined
children
Snippet
The children content to render.
Default: ——undefined
child
Snippet
Use render delegation to render your own element. See Child Snippet docs for more information.
Default: ——undefined
Data Attribute
Value
Description
data-select-group
''
Present on the group element.
Select.GroupHeading
A heading for the parent select group. This is used to describe a group of related select items.
Property
Type
Description
ref$bindable
HTMLDivElement
The underlying DOM element being rendered. You can bind to this to get a reference to the element.
Default: ——undefined
children
Snippet
The children content to render.
Default: ——undefined
child
Snippet
Use render delegation to render your own element. See Child Snippet docs for more information.
Default: ——undefined
Data Attribute
Value
Description
data-select-group-heading
''
Present on the group heading element.
Select.Arrow
An optional arrow element which points to the content when open.
Property
Type
Description
width
number
The width of the arrow in pixels.
Default: 8
height
number
The height of the arrow in pixels.
Default: 8
ref$bindable
HTMLDivElement
The underlying DOM element being rendered. You can bind to this to get a reference to the element.
Default: ——undefined
children
Snippet
The children content to render.
Default: ——undefined
child
Snippet
Use render delegation to render your own element. See Child Snippet docs for more information.