Base UI

An accessible popup anchored to a button.

import * as React from 'react';
import { Popover } from '@base-ui-components/react/popover';
import styles from './index.module.css';

export default function ExamplePopover() {
  return (
    <Popover.Root>
      <Popover.Trigger className={styles.IconButton}>
        <BellIcon aria-label="Notifications" className={styles.Icon} />
      </Popover.Trigger>
      <Popover.Portal>
        <Popover.Positioner sideOffset={8}>
          <Popover.Popup className={styles.Popup}>
            <Popover.Arrow className={styles.Arrow}>
              <ArrowSvg />
            </Popover.Arrow>
            <Popover.Title className={styles.Title}>Notifications</Popover.Title>
            <Popover.Description className={styles.Description}>
              You are all caught up. Good job!
            </Popover.Description>
          </Popover.Popup>
        </Popover.Positioner>
      </Popover.Portal>
    </Popover.Root>
  );
}

function ArrowSvg(props: React.ComponentProps<'svg'>) {
  return (
    <svg width="20" height="10" viewBox="0 0 20 10" fill="none" {...props}>
      <path
        d="M9.66437 2.60207L4.80758 6.97318C4.07308 7.63423 3.11989 8 2.13172 8H0V10H20V8H18.5349C17.5468 8 16.5936 7.63423 15.8591 6.97318L11.0023 2.60207C10.622 2.2598 10.0447 2.25979 9.66437 2.60207Z"
        className={styles.ArrowFill}
      />
      <path
        d="M8.99542 1.85876C9.75604 1.17425 10.9106 1.17422 11.6713 1.85878L16.5281 6.22989C17.0789 6.72568 17.7938 7.00001 18.5349 7.00001L15.89 7L11.0023 2.60207C10.622 2.2598 10.0447 2.2598 9.66436 2.60207L4.77734 7L2.13171 7.00001C2.87284 7.00001 3.58774 6.72568 4.13861 6.22989L8.99542 1.85876Z"
        className={styles.ArrowOuterStroke}
      />
      <path
        d="M10.3333 3.34539L5.47654 7.71648C4.55842 8.54279 3.36693 9 2.13172 9H0V8H2.13172C3.11989 8 4.07308 7.63423 4.80758 6.97318L9.66437 2.60207C10.0447 2.25979 10.622 2.2598 11.0023 2.60207L15.8591 6.97318C16.5936 7.63423 17.5468 8 18.5349 8H20V9H18.5349C17.2998 9 16.1083 8.54278 15.1901 7.71648L10.3333 3.34539Z"
        className={styles.ArrowInnerStroke}
      />
    </svg>
  );
}

function BellIcon(props: React.ComponentProps<'svg'>) {
  return (
    <svg fill="currentcolor" width="20" height="20" viewBox="0 0 16 16" {...props}>
      <path d="M 8 1 C 7.453125 1 7 1.453125 7 2 L 7 3.140625 C 5.28125 3.589844 4 5.144531 4 7 L 4 10.984375 C 4 10.984375 3.984375 11.261719 3.851563 11.519531 C 3.71875 11.78125 3.558594 12 3 12 L 3 13 L 13 13 L 13 12 C 12.40625 12 12.253906 11.78125 12.128906 11.53125 C 12.003906 11.277344 12 11.003906 12 11.003906 L 12 7 C 12 5.144531 10.71875 3.589844 9 3.140625 L 9 2 C 9 1.453125 8.546875 1 8 1 Z M 8 13 C 7.449219 13 7 13.449219 7 14 C 7 14.550781 7.449219 15 8 15 C 8.550781 15 9 14.550781 9 14 C 9 13.449219 8.550781 13 8 13 Z M 8 4 C 9.664063 4 11 5.335938 11 7 L 11 10.996094 C 11 10.996094 10.988281 11.472656 11.234375 11.96875 C 11.238281 11.980469 11.246094 11.988281 11.25 12 L 4.726563 12 C 4.730469 11.992188 4.738281 11.984375 4.742188 11.980469 C 4.992188 11.488281 5 11.015625 5 11.015625 L 5 7 C 5 5.335938 6.335938 4 8 4 Z" />
    </svg>
  );
}

Anatomy

Import the component and assemble its parts:

Anatomy

import { Popover } from '@base-ui-components/react/popover';

<Popover.Root>
  <Popover.Trigger />
  <Popover.Portal>
    <Popover.Backdrop />
    <Popover.Positioner>
      <Popover.Popup>
        <Popover.Arrow />
        <Popover.Title />
        <Popover.Description />
        <Popover.Close />
      </Popover.Popup>
    </Popover.Positioner>
  </Popover.Portal>
</Popover.Root>

API reference

Root

Groups all parts of the popover. Doesn’t render its own HTML element.

defaultOpen

boolean

false

Name: defaultOpen
Description: Whether the popover is initially open.

To render a controlled popover, use the open prop instead.
Type: boolean | undefined
Default: false

open

boolean

—

Name: open
Description: Whether the popover is currently open.
Type: boolean | undefined

onOpenChange

function

—

Name: onOpenChange
Description: Event handler called when the popover is opened or closed.
Type: | (( open: boolean, eventDetails: Popover.Root.ChangeEventDetails, ) => void) | undefined

actionsRef

RefObject<Popover.Root.Actions>

—

Name: actionsRef
Description: A ref to imperative actions.

unmount: When specified, the popover will not be unmounted when closed. Instead, the unmount function must be called to unmount the popover manually. Useful when the popover's animation is controlled by an external library.
Type: React.RefObject<Popover.Root.Actions> | undefined

Name: modal
Description: Determines if the popover enters a modal state when open.

true: user interaction is limited to the popover: document page scroll is locked, and pointer interactions on outside elements are disabled.

false: user interaction with the rest of the document is allowed.

'trap-focus': focus is trapped inside the popover, but document page scroll is not locked and pointer interactions outside of it remain enabled.
Type: boolean | 'trap-focus' | undefined
Default: false

onOpenChangeComplete

function

—

Name: onOpenChangeComplete
Description: Event handler called after any animations complete when the popover is opened or closed.
Type: ((open: boolean) => void) | undefined

openOnHover

boolean

false

Name: openOnHover
Description: Whether the popover should also open when the trigger is hovered.
Type: boolean | undefined
Default: false

delay

number

300

Name: delay
Description: How long to wait before the popover may be opened on hover. Specified in milliseconds.

Requires the openOnHover prop.
Type: number | undefined
Default: 300

closeDelay

number

0

Name: closeDelay
Description: How long to wait before closing the popover that was opened on hover. Specified in milliseconds.

Requires the openOnHover prop.
Type: number | undefined
Default: 0

children

ReactNode

—

Name: children
Type: React.ReactNode

Trigger

A button that opens the popover. Renders a <button> element.

nativeButton

boolean

true

Name: nativeButton
Description: Whether the component renders a native <button> element when replacing it via the render prop. Set to false if the rendered element is not a button (e.g. <div>).
Type: boolean | undefined
Default: true

className

string | function

—

Name: className
Description: CSS class applied to the element, or a function that returns a class based on the component’s state.
Type: string | ((state: Popover.Trigger.State) => string)

render

ReactElement | function

—

Name: render
Description: Allows you to replace the component’s HTML element with a different tag, or compose it with another component.

Accepts a ReactElement or a function that returns the element to render.
Type: | ReactElement | (( props: HTMLProps, state: Popover.Trigger.State, ) => ReactElement)

data-popup-open

Present when the corresponding popover is open.

data-pressed

Present when the trigger is pressed.

Attribute	Description
`data-popup-open`	Present when the corresponding popover is open.
`data-pressed`	Present when the trigger is pressed.

Backdrop

An overlay displayed beneath the popover. Renders a <div> element.

className

string | function

—

Name: className
Description: CSS class applied to the element, or a function that returns a class based on the component’s state.
Type: | string | ((state: Popover.Backdrop.State) => string)

render

ReactElement | function

—

Name: render
Description: Allows you to replace the component’s HTML element with a different tag, or compose it with another component.

Accepts a ReactElement or a function that returns the element to render.
Type: | ReactElement | (( props: HTMLProps, state: Popover.Backdrop.State, ) => ReactElement)

data-open

Present when the popup is open.

data-closed

Present when the popup is closed.

data-starting-style

Present when the popup is animating in.

data-ending-style

Present when the popup is animating out.

Attribute	Description
`data-open`	Present when the popup is open.
`data-closed`	Present when the popup is closed.
`data-starting-style`	Present when the popup is animating in.
`data-ending-style`	Present when the popup is animating out.

Portal

A portal element that moves the popup to a different part of the DOM. By default, the portal element is appended to <body>.

container

Union

—

Name: container
Description: A parent element to render the portal element into.
Type: | HTMLElement | ShadowRoot | React.RefObject<HTMLElement | ShadowRoot | null> | null | undefined

children

ReactNode

—

Name: children
Type: React.ReactNode

keepMounted

boolean

false

Name: keepMounted
Description: Whether to keep the portal mounted in the DOM while the popup is hidden.
Type: boolean | undefined
Default: false

Positioner

Positions the popover against the trigger. Renders a <div> element.

collisionAvoidance

CollisionAvoidance

—

Name: collisionAvoidance
Description: Determines how to handle collisions when positioning the popup.
Type: | { side?: 'none' | 'flip' align?: 'shift' | 'none' | 'flip' fallbackAxisSide?: 'none' | 'start' | 'end' } | { side?: 'shift' | 'none' align?: 'shift' | 'none' fallbackAxisSide?: 'none' | 'start' | 'end' } | undefined
Example: <Positioner collisionAvoidance={{ side: 'shift', align: 'shift', fallbackAxisSide: 'none', }} />

align

Align

'center'

Name: align
Description: How to align the popup relative to the specified side.
Type: 'center' | 'start' | 'end' | undefined
Default: 'center'

alignOffset

number | OffsetFunction

0

Name: alignOffset
Description: Additional offset along the alignment axis in pixels. Also accepts a function that returns the offset to read the dimensions of the anchor and positioner elements, along with its side and alignment.

The function takes a data object parameter with the following properties:

data.anchor: the dimensions of the anchor element with properties width and height.

data.positioner: the dimensions of the positioner element with properties width and height.

data.side: which side of the anchor element the positioner is aligned against.

data.align: how the positioner is aligned relative to the specified side.
Type: | number | ((data: { side: Side align: Align anchor: { width: number; height: number } positioner: { width: number; height: number } }) => number) | undefined
Default: 0
Example: <Positioner alignOffset={({ side, align, anchor, positioner }) => { return side === 'top' || side === 'bottom' ? anchor.width : anchor.height; }} />

side

Side

'bottom'

Name: side
Description: Which side of the anchor element to align the popup against. May automatically change to avoid collisions.
Type: | 'top' | 'bottom' | 'left' | 'right' | 'inline-end' | 'inline-start' | undefined
Default: 'bottom'

sideOffset

number | OffsetFunction

0

Name: sideOffset
Description: Distance between the anchor and the popup in pixels. Also accepts a function that returns the distance to read the dimensions of the anchor and positioner elements, along with its side and alignment.

The function takes a data object parameter with the following properties:

data.anchor: the dimensions of the anchor element with properties width and height.

data.positioner: the dimensions of the positioner element with properties width and height.

data.side: which side of the anchor element the positioner is aligned against.

data.align: how the positioner is aligned relative to the specified side.
Type: | number | ((data: { side: Side align: Align anchor: { width: number; height: number } positioner: { width: number; height: number } }) => number) | undefined
Default: 0
Example: <Positioner sideOffset={({ side, align, anchor, positioner }) => { return side === 'top' || side === 'bottom' ? anchor.height : anchor.width; }} />

arrowPadding

number

5

Name: arrowPadding
Description: Minimum distance to maintain between the arrow and the edges of the popup.

Use it to prevent the arrow element from hanging out of the rounded corners of a popup.
Type: number | undefined
Default: 5

anchor

Union

—

Name: anchor
Description: An element to position the popup against. By default, the popup will be positioned against the trigger.
Type: | Element | React.RefObject<Element | null> | VirtualElement | (() => Element | VirtualElement | null) | null | undefined

collisionBoundary

Boundary

'clipping-ancestors'

Name: collisionBoundary
Description: An element or a rectangle that delimits the area that the popup is confined to.
Type: | Element | 'clipping-ancestors' | Element[] | Rect | undefined
Default: 'clipping-ancestors'

collisionPadding

Padding

5

Name: collisionPadding
Description: Additional space to maintain from the edge of the collision boundary.
Type: | { top?: number right?: number bottom?: number left?: number } | number | undefined
Default: 5

sticky

boolean

false

Name: sticky
Description: Whether to maintain the popup in the viewport after the anchor element was scrolled out of view.
Type: boolean | undefined
Default: false

positionMethod

'fixed' | 'absolute'

'absolute'

Name: positionMethod
Description: Determines which CSS position property to use.
Type: 'fixed' | 'absolute' | undefined
Default: 'absolute'

trackAnchor

boolean

true

Name: trackAnchor
Description: Whether the popup tracks any layout shift of its positioning anchor.
Type: boolean | undefined
Default: true

className

string | function

—

Name: className
Description: CSS class applied to the element, or a function that returns a class based on the component’s state.
Type: | string | ((state: Popover.Positioner.State) => string)

render

ReactElement | function

—

Name: render
Description: Allows you to replace the component’s HTML element with a different tag, or compose it with another component.

Accepts a ReactElement or a function that returns the element to render.
Type: | ReactElement | (( props: HTMLProps, state: Popover.Positioner.State, ) => ReactElement)

data-open

Present when the popup is open.

data-closed

Present when the popup is closed.

data-anchor-hidden

Present when the anchor is hidden.

data-align

Indicates how the popup is aligned relative to specified side.

data-side

Indicates which side the popup is positioned relative to the trigger.

Attribute	Description
`data-open`	Present when the popup is open.
`data-closed`	Present when the popup is closed.
`data-anchor-hidden`	Present when the anchor is hidden.
`data-align`	Indicates how the popup is aligned relative to specified side.
`data-side`	Indicates which side the popup is positioned relative to the trigger.

--anchor-height

The anchor's height.

--anchor-width

The anchor's width.

--available-height

The available height between the trigger and the edge of the viewport.

--available-width

The available width between the trigger and the edge of the viewport.

--transform-origin

The coordinates that this element is anchored to. Used for animations and transitions.

CSS Variable	Description
`--anchor-height`	The anchor's height.
`--anchor-width`	The anchor's width.
`--available-height`	The available height between the trigger and the edge of the viewport.
`--available-width`	The available width between the trigger and the edge of the viewport.
`--transform-origin`	The coordinates that this element is anchored to. Used for animations and transitions.

A container for the popover contents. Renders a <div> element.

initialFocus

Union

—

Name: initialFocus
Description: Determines the element to focus when the popover is opened.

false: Do not move focus.

true: Move focus based on the default behavior (first tabbable element or popup).

RefObject: Move focus to the ref element.

function: Called with the interaction type (mouse, touch, pen, or keyboard). Return an element to focus, true to use the default behavior, or false/undefined to do nothing.
Type: | boolean | React.RefObject<HTMLElement | null> | (( openType: InteractionType, ) => boolean | void | HTMLElement | null) | undefined

finalFocus

Union

—

Name: finalFocus
Description: Determines the element to focus when the popover is closed.

false: Do not move focus.

true: Move focus based on the default behavior (trigger or previously focused element).

RefObject: Move focus to the ref element.

function: Called with the interaction type (mouse, touch, pen, or keyboard). Return an element to focus, true to use the default behavior, or false/undefined to do nothing.
Type: | boolean | React.RefObject<HTMLElement | null> | (( closeType: InteractionType, ) => boolean | void | HTMLElement | null) | undefined

className

string | function

—

Name: className
Description: CSS class applied to the element, or a function that returns a class based on the component’s state.
Type: string | ((state: Popover.Popup.State) => string)

render

ReactElement | function

—

Name: render
Description: Allows you to replace the component’s HTML element with a different tag, or compose it with another component.

Accepts a ReactElement or a function that returns the element to render.
Type: | ReactElement | (( props: HTMLProps, state: Popover.Popup.State, ) => ReactElement)

data-open

Present when the popup is open.

data-closed

Present when the popup is closed.

data-align

Indicates how the popup is aligned relative to specified side.

data-instant

Present if animations should be instant.

data-side

Indicates which side the popup is positioned relative to the trigger.

data-starting-style

Present when the popup is animating in.

data-ending-style

Present when the popup is animating out.

Attribute	Description
`data-open`	Present when the popup is open.
`data-closed`	Present when the popup is closed.
`data-align`	Indicates how the popup is aligned relative to specified side.
`data-instant`	Present if animations should be instant.
`data-side`	Indicates which side the popup is positioned relative to the trigger.
`data-starting-style`	Present when the popup is animating in.
`data-ending-style`	Present when the popup is animating out.

Arrow

Displays an element positioned against the popover anchor. Renders a <div> element.

className

string | function

—

Name: className
Description: CSS class applied to the element, or a function that returns a class based on the component’s state.
Type: string | ((state: Popover.Arrow.State) => string)

render

ReactElement | function

—

Name: render
Description: Allows you to replace the component’s HTML element with a different tag, or compose it with another component.

Accepts a ReactElement or a function that returns the element to render.
Type: | ReactElement | (( props: HTMLProps, state: Popover.Arrow.State, ) => ReactElement)

data-open

Present when the popup is open.

data-closed

Present when the popup is closed.

data-uncentered

Present when the popover arrow is uncentered.

data-anchor-hidden

Present when the anchor is hidden.

data-align

Indicates how the popup is aligned relative to specified side.

data-side

Indicates which side the popup is positioned relative to the trigger.

Attribute	Description
`data-open`	Present when the popup is open.
`data-closed`	Present when the popup is closed.
`data-uncentered`	Present when the popover arrow is uncentered.
`data-anchor-hidden`	Present when the anchor is hidden.
`data-align`	Indicates how the popup is aligned relative to specified side.
`data-side`	Indicates which side the popup is positioned relative to the trigger.

Title

A heading that labels the popover. Renders an <h2> element.

className

string | function

—

Name: className
Description: CSS class applied to the element, or a function that returns a class based on the component’s state.
Type: string | ((state: Popover.Title.State) => string)

render

ReactElement | function

—

Name: render
Description: Allows you to replace the component’s HTML element with a different tag, or compose it with another component.

Accepts a ReactElement or a function that returns the element to render.
Type: | ReactElement | (( props: HTMLProps, state: Popover.Title.State, ) => ReactElement)

Description

A paragraph with additional information about the popover. Renders a <p> element.

className

string | function

—

Name: className
Description: CSS class applied to the element, or a function that returns a class based on the component’s state.
Type: | string | ((state: Popover.Description.State) => string)

render

ReactElement | function

—

Name: render
Description: Allows you to replace the component’s HTML element with a different tag, or compose it with another component.

Accepts a ReactElement or a function that returns the element to render.
Type: | ReactElement | (( props: HTMLProps, state: Popover.Description.State, ) => ReactElement)

Close

A button that closes the popover. Renders a <button> element.

nativeButton

boolean

true

Name: nativeButton
Description: Whether the component renders a native <button> element when replacing it via the render prop. Set to false if the rendered element is not a button (e.g. <div>).
Type: boolean | undefined
Default: true

className

string | function

—

Name: className
Description: CSS class applied to the element, or a function that returns a class based on the component’s state.
Type: string | ((state: Popover.Close.State) => string)

render

ReactElement | function

—

Name: render
Description: Allows you to replace the component’s HTML element with a different tag, or compose it with another component.

Accepts a ReactElement or a function that returns the element to render.
Type: | ReactElement | (( props: HTMLProps, state: Popover.Close.State, ) => ReactElement)