Select

An accessible dropdown built on Radix UI, styled to match the design system. Compose a trigger, value, and items; pair with a label and hint/error text for full form fields.

Basic usage

Compose SelectTrigger, SelectValue, and SelectItem children.

Country

Trigger sizes

The trigger has two heights. size="default" is 36px and lines up with Input and Button; size="sm" is 32px for toolbars and table filter rows. Both set their text the way every field does since 3.13.4 — 16px below md, 14px from md up — so a trigger needs no text class of its own (why).

Groups & separators

Long lists read better in sections. Wrap items in a SelectGroup, title each one with SelectLabel, and divide them with SelectSeparator. Row spacing comes from the item itself (mt-1 first:mt-0), so it stays identical whether an item sits inside a group or directly in the list. A list long enough to overflow the viewport also grows arrows at both ends — SelectScrollUpButton and SelectScrollDownButton. Both are exported, but SelectContent already renders them for you; import them only if you are assembling your own content shell.

States

Pair the select with a label and hint/error text. Set aria-invalid on the trigger for the error style.

Region

Choose your primary region.

Country

Please select a country.

The “nothing selected” row

Radix reserves the empty string for clearing a selection, so <SelectItem value="" /> throws. The package ships one shared sentinel instead of leaving every app to invent its own: SELECT_EMPTY_VALUE plus toSelectValue / fromSelectValue to convert at the boundary. Your model keeps '' and the sentinel never reaches a server payload.

model value: ''

Props

Select root props (forwarded to Radix):

Prop	Kiểu	Mặc định	Mô tả
`value`	string	—	Controlled selected value. Pair with onValueChange.
`defaultValue`	string	—	Initial value when the select is uncontrolled.
`onValueChange`	(value: string) => void	—	Fires when the user picks a different item.
`open / defaultOpen`	boolean	—	Controlled / uncontrolled open state of the listbox.
`onOpenChange`	(open: boolean) => void	—	Fires when the listbox opens or closes.
`disabled`	boolean	`false`	Disables the whole control.
`required`	boolean	`false`	Marks the control required when it takes part in a native form.
`name`	string	—	Name of the hidden native input rendered for form submission.

SelectTrigger props:

Prop	Kiểu	Mặc định	Mô tả
`size`	'sm' \| 'default'	`'default'`	Trigger height — sm is 32px, default is 36px. Rendered as data-size on the element.
`aria-invalid`	boolean	—	Switches the border to --destructive-ink and adds the destructive ring.
`className`	string	—	Additional Tailwind classes merged onto the trigger.
`...rest`	Radix SelectTrigger props	—	Everything else is forwarded to the Radix trigger. The chevron icon is rendered by the component.

The remaining parts:

Prop	Kiểu	Mặc định	Mô tả
`SelectValue placeholder`	ReactNode	—	Shown while nothing is selected; picks up the muted-foreground colour via data-placeholder on the trigger.
`SelectContent position`	'popper' \| 'item-aligned'	`'popper'`	Popper mode anchors the list under the trigger and matches its width; scroll buttons are rendered automatically.
`SelectItem value`bắt buộc	string	—	Value written back by onValueChange. Radix rejects an empty string — use SELECT_EMPTY_VALUE for a "none" row.
`SelectItem disabled`	boolean	`false`	Dims the row and skips it during keyboard navigation.
`SelectGroup / SelectLabel`	div / label parts	—	Wrap related items in a group and title it with a label; the label is announced as the group name.
`SelectSeparator`	div part	—	A one-pixel divider between groups. Pointer events are disabled so it can never swallow a click.

Accessibility

Built on Radix UI Select — full keyboard navigation and typeahead.
Focus is managed and trapped within the open listbox.
Associate a <label> with the trigger via id / aria-labelledby.
The trigger carries no fill of its own beyond bg-background, so its border is the only thing outlining the control. Each state gets its own role token, and every one of them is darker than rest, never lighter: border-input at rest, border-control-edge-strong on hover, border-primary-ink on focus, and border-destructive-ink when aria-invalid is set. Under data-contrast="high" those four steps measure 3.83:1, 10.55:1, 6.51:1 and 7.15:1, all past the 3:1 threshold of WCAG 1.4.11. The default palette keeps the lighter steps in light mode — 1.16:1 at rest, 1.62:1 on hover, 1.86:1 on focus — so what it guarantees there is the ordering, not the ratio.
The selected item is marked by a check mark, not by its background. The highlight tint (--accent, shared with the hovered row) sits at roughly 1:1 against the popover and is a soft cue only; the check is a shape, satisfying WCAG 1.4.1.