useRender

Hook for enabling a render prop in custom components.

The useRender hook lets you build custom components that provide a render prop to override the default rendered element.

Examples

A render prop for a custom Text component lets consumers use it to replace the default rendered p element with a different tag or component.

Text component rendered as a paragraph tag

Text component rendered as a strong tag

index.tsx index.module.css theme.css

'use client';
import { useRender } from '@base-ui/react/use-render';
import { mergeProps } from '@base-ui/react/merge-props';
import styles from './index.module.css';

interface TextProps extends useRender.ComponentProps<'p'> {}

function Text(props: TextProps) {
  const { render, ...otherProps } = props;

  const element = useRender({
    defaultTagName: 'p',
    render,
    props: mergeProps<'p'>({ className: styles.Text }, otherProps),
  });

  return element;
}

export default function ExampleText() {
  return (
    <div>
      <Text>Text component rendered as a paragraph tag</Text>
      <Text render={<strong />}>Text component rendered as a strong tag</Text>
    </div>
  );
}

The callback version of the render prop enables more control of how props are spread, and also passes the internal state of a component.

index.tsx index.module.css theme.css

'use client';
import * as React from 'react';
import { useRender } from '@base-ui/react/use-render';
import { mergeProps } from '@base-ui/react/merge-props';
import styles from './index.module.css';

interface CounterState {
  odd: boolean;
}

interface CounterProps extends useRender.ComponentProps<'button', CounterState> {}

function Counter(props: CounterProps) {
  const { render, ...otherProps } = props;

  const [count, setCount] = React.useState(0);
  const odd = count % 2 === 1;
  const state = React.useMemo(() => ({ odd }), [odd]);

  const defaultProps: useRender.ElementProps<'button'> = {
    className: styles.Button,
    type: 'button',
    children: (
      <React.Fragment>
        Counter: <span>{count}</span>
      </React.Fragment>
    ),
    onClick() {
      setCount((prev) => prev + 1);
    },
    'aria-label': `Count is ${count}, click to increase.`,
  };

  const element = useRender({
    defaultTagName: 'button',
    render,
    state,
    props: mergeProps<'button'>(defaultProps, otherProps),
  });

  return element;
}

export default function ExampleCounter() {
  return (
    <Counter
      render={(props, state) => (
        <button {...props}>
          {props.children}
          <span className={styles.suffix}>{state.odd ? '👎' : '👍'}</span>
        </button>
      )}
    />
  );
}

Merging props

The mergeProps function merges two or more sets of React props together. It safely merges three types of props:

Event handlers, so that all are invoked
className strings
style properties

mergeProps merges objects from left to right, so that subsequent objects’ properties in the arguments overwrite previous ones. Merging props is useful when creating custom components, as well as inside the callback version of the render prop for any Base UI component.

Using mergeProps in the render callback

import { mergeProps } from '@base-ui/react/merge-props';
import styles from './index.module.css';

function Button() {
  return (
    <Component
      render={(props, state) => (
        <button
          {...mergeProps<'button'>(props, {
            className: styles.Button,
          })}
        />
      )}
    />
  );
}

Merging refs

When building custom components, you often need to control a ref internally while still letting external consumers pass their own—merging refs lets both parties have access to the underlying DOM element. The ref option in useRender enables this, which holds an array of refs to be merged together.

In React 19, React.forwardRef() is not needed when building primitive components, as the external ref prop is already contained inside props. Your internal ref can be passed to ref to be merged with props.ref:

React 19

function Text({ render, ...props }: TextProps) {
  const internalRef = React.useRef<HTMLElement | null>(null);

  const element = useRender({
    defaultTagName: 'p',
    ref: internalRef,
    props,
    render,
  });

  return element;
}

In older versions of React, you need to use React.forwardRef() and add the forwarded ref to the ref array along with your own internal ref.

The examples above assume React 19, and should be modified to use React.forwardRef() to support React 18 and 17.

React 18 and 17

const Text = React.forwardRef(function Text(
  { render, ...props }: TextProps,
  forwardedRef: React.ForwardedRef<HTMLElement>,
) {
  const internalRef = React.useRef<HTMLElement | null>(null);

  const element = useRender({
    defaultTagName: 'p',
    ref: [forwardedRef, internalRef],
    props,
    render,
  });

  return element;
});

TypeScript

To type props, there are two interfaces:

useRender.ComponentProps for a component’s external (public) props. It types the render prop and HTML attributes.
useRender.ElementProps for the element’s internal (private) props. It types HTML attributes alone.

Typing props

interface ButtonProps extends useRender.ComponentProps<'button'> {}

function Button({ render, ...props }: ButtonProps) {
  const defaultProps: useRender.ElementProps<'button'> = {
    className: styles.Button,
    type: 'button',
    children: 'Click me',
  };

  const element = useRender({
    defaultTagName: 'button',
    render,
    props: mergeProps<'button'>(defaultProps, props),
  });

  return element;
}

Migrating from Radix UI

Radix UI uses an asChild prop, while Base UI uses a render prop. Learn more about how composition works in Base UI in the composition guide.

In Radix UI, the Slot component lets you implement an asChild prop.

Radix UI Slot component

import { Slot } from 'radix-ui';

function Button({ asChild, ...props }) {
  const Comp = asChild ? Slot.Root : 'button';
  return <Comp {...props} />;
}

// Usage
<Button asChild>
  <MyButton className="primary">Submit</MyButton>
</Button>

In Base UI, useRender lets you implement a render prop. The example below is the equivalent implementation to the Radix example above.

Base UI render prop

import { useRender } from '@base-ui/react/use-render';

function Button({ render, ...props }) {
  return useRender({
    defaultTagName: 'button',
    render,
    props,
  });
}

// Usage
<Button render={<MyButton className="primary" />}>Submit</Button>

Render prop and polymorphism

The render prop is primarily designed for composing event handlers and behavioral props. In most cases it should render the same tag as the default element.

Using render for polymorphism (rendering a different tag) requires more care, as some default props may not be valid on the new element. For example, type="button" is only valid on a <button>. Since the component can’t know what element render will produce at render time and before hydration, props like these need an explicit signal. This is why Base UI’s Button provides a nativeButton prop to control which defaults are applied.

API reference

Usage

const element = useRender({
  // Input parameters
});

Parameters

useRender.Parameters

renderReactElement | function

Name: render
Description: The React element or a function that returns one to override the default element.
Type: UseRenderRenderProp<TState> | undefined

refUnion

Name: ref
Description: The ref to apply to the rendered element.
Type: | React.Ref<Element>[] | React.Ref<Element> | undefined

stateTState

Name: state
Description: The state of the component, passed as the second argument to the render callback. State properties are automatically converted to data-* attributes.
Type: TState | undefined

stateAttributesMappingStateAttributesMapping<TState>

Name: stateAttributesMapping
Description: Custom mapping for converting state properties to data-* attributes.
Type: StateAttributesMapping<TState> | undefined
Example: { isActive: (value) => (value ? { 'data-is-active': '' } : null) }

propsRecord<string, unknown>

Name: props
Description: Props to be spread on the rendered element. They are merged with the internal props of the component, so that event handlers are merged, className strings and style properties are joined, while other external props overwrite the internal ones.
Type: Record<string, unknown> | undefined

enabledboolean

Name: enabled
Description: If false, the hook will skip most of its internal logic and return null. This is useful for rendering a component conditionally.
Type: boolean | undefined

defaultTagNameUnion

Name: defaultTagName
Description: The default tag name to use for the rendered element when render is not provided.
Type: | 'symbol' | 'object' | 'a' | 'abbr' | 'address' | 'area' | 'article' | 'aside' | 'audio' | 'b' | 'base' | 'bdi' | 'bdo' | 'big' | 'blockquote' | 'body' | 'br' | 'button' | 'canvas' | 'caption' | 'center' | 'cite' | 'code' | 'col' | 'colgroup' | 'data' | 'datalist' | 'dd' | 'del' | 'details' | 'dfn' | 'dialog' | 'div' | 'dl' | 'dt' | 'em' | 'embed' | 'fieldset' | 'figcaption' | 'figure' | 'footer' | 'form' | 'h1' | 'h2' | 'h3' | 'h4' | 'h5' | 'h6' | 'head' | 'header' | 'hgroup' | 'hr' | 'html' | 'i' | 'iframe' | 'img' | 'input' | 'ins' | 'kbd' | 'keygen' | 'label' | 'legend' | 'li' | 'link' | 'main' | 'map' | 'mark' | 'menu' | 'menuitem' | 'meta' | 'meter' | 'nav' | 'noindex' | 'noscript' | 'ol' | 'optgroup' | 'option' | 'output' | 'p' | 'param' | 'picture' | 'pre' | 'progress' | 'q' | 'rp' | 'rt' | 'ruby' | 's' | 'samp' | 'search' | 'slot' | 'script' | 'section' | 'select' | 'small' | 'source' | 'span' | 'strong' | 'style' | 'sub' | 'summary' | 'sup' | 'table' | 'template' | 'tbody' | 'td' | 'textarea' | 'tfoot' | 'th' | 'thead' | 'time' | 'title' | 'tr' | 'track' | 'u' | 'ul' | 'var' | 'video' | 'wbr' | 'webview' | 'svg' | 'animate' | 'animateMotion' | 'animateTransform' | 'circle' | 'clipPath' | 'defs' | 'desc' | 'ellipse' | 'feBlend' | 'feColorMatrix' | 'feComponentTransfer' | 'feComposite' | 'feConvolveMatrix' | 'feDiffuseLighting' | 'feDisplacementMap' | 'feDistantLight' | 'feDropShadow' | 'feFlood' | 'feFuncA' | 'feFuncB' | 'feFuncG' | 'feFuncR' | 'feGaussianBlur' | 'feImage' | 'feMerge' | 'feMergeNode' | 'feMorphology' | 'feOffset' | 'fePointLight' | 'feSpecularLighting' | 'feSpotLight' | 'feTile' | 'feTurbulence' | 'filter' | 'foreignObject' | 'g' | 'image' | 'line' | 'linearGradient' | 'marker' | 'mask' | 'metadata' | 'mpath' | 'path' | 'pattern' | 'polygon' | 'polyline' | 'radialGradient' | 'rect' | 'set' | 'stop' | 'switch' | 'text' | 'textPath' | 'tspan' | 'use' | 'view' | undefined

Return value

ReactElement | null

useRender.StateHide

type useRenderState = {}

useRender.ComponentPropsHide

type useRenderComponentProps<
  ElementType extends React.ElementType,
  TState = {},
  RenderFunctionProps = HTMLProps,
> = React.ComponentPropsWithRef<ElementType> & {
  render?: ReactElement | ((props: RenderFunctionProps, state: TState) => ReactElement);
}

useRender.ElementPropsHide

type useRenderElementProps =
  | (React.PropsWithoutRef<Props> & React.RefAttributes<R | any>)
  | Props
  | React.ComponentProps<React.ElementType>

useRender.ParametersHide

type useRenderParameters<
  TState,
  RenderedElementType extends Element,
  Enabled extends boolean | undefined,
> = {
  /** The React element or a function that returns one to override the default element. */
  render?: UseRenderRenderProp<TState>;
  /** The ref to apply to the rendered element. */
  ref?: React.Ref<RenderedElementType>[] | React.Ref<RenderedElementType>;
  /**
   * The state of the component, passed as the second argument to the `render` callback.
   * State properties are automatically converted to data-* attributes.
   */
  state?: TState;
  /**
   * Custom mapping for converting state properties to data-* attributes.
   * @example { isActive: (value) => (value ? { 'data-is-active': '' } : null) }
   */
  stateAttributesMapping?: StateAttributesMapping<TState>;
  /**
   * Props to be spread on the rendered element.
   * They are merged with the internal props of the component, so that event handlers
   * are merged, `className` strings and `style` properties are joined, while other external props overwrite the
   * internal ones.
   */
  props?: Record<string, unknown>;
  /**
   * If `false`, the hook will skip most of its internal logic and return `null`.
   * This is useful for rendering a component conditionally.
   * @default true
   */
  enabled?: boolean | undefined;
  /**
   * The default tag name to use for the rendered element when `render` is not provided.
   * @default 'div'
   */
  defaultTagName?:
    | 'symbol'
    | 'object'
    | 'a'
    | 'abbr'
    | 'address'
    | 'area'
    | 'article'
    | 'aside'
    | 'audio'
    | 'b'
    | 'base'
    | 'bdi'
    | 'bdo'
    | 'big'
    | 'blockquote'
    | 'body'
    | 'br'
    | 'button'
    | 'canvas'
    | 'caption'
    | 'center'
    | 'cite'
    | 'code'
    | 'col'
    | 'colgroup'
    | 'data'
    | 'datalist'
    | 'dd'
    | 'del'
    | 'details'
    | 'dfn'
    | 'dialog'
    | 'div'
    | 'dl'
    | 'dt'
    | 'em'
    | 'embed'
    | 'fieldset'
    | 'figcaption'
    | 'figure'
    | 'footer'
    | 'form'
    | 'h1'
    | 'h2'
    | 'h3'
    | 'h4'
    | 'h5'
    | 'h6'
    | 'head'
    | 'header'
    | 'hgroup'
    | 'hr'
    | 'html'
    | 'i'
    | 'iframe'
    | 'img'
    | 'input'
    | 'ins'
    | 'kbd'
    | 'keygen'
    | 'label'
    | 'legend'
    | 'li'
    | 'link'
    | 'main'
    | 'map'
    | 'mark'
    | 'menu'
    | 'menuitem'
    | 'meta'
    | 'meter'
    | 'nav'
    | 'noindex'
    | 'noscript'
    | 'ol'
    | 'optgroup'
    | 'option'
    | 'output'
    | 'p'
    | 'param'
    | 'picture'
    | 'pre'
    | 'progress'
    | 'q'
    | 'rp'
    | 'rt'
    | 'ruby'
    | 's'
    | 'samp'
    | 'search'
    | 'slot'
    | 'script'
    | 'section'
    | 'select'
    | 'small'
    | 'source'
    | 'span'
    | 'strong'
    | 'style'
    | 'sub'
    | 'summary'
    | 'sup'
    | 'table'
    | 'template'
    | 'tbody'
    | 'td'
    | 'textarea'
    | 'tfoot'
    | 'th'
    | 'thead'
    | 'time'
    | 'title'
    | 'tr'
    | 'track'
    | 'u'
    | 'ul'
    | 'var'
    | 'video'
    | 'wbr'
    | 'webview'
    | 'svg'
    | 'animate'
    | 'animateMotion'
    | 'animateTransform'
    | 'circle'
    | 'clipPath'
    | 'defs'
    | 'desc'
    | 'ellipse'
    | 'feBlend'
    | 'feColorMatrix'
    | 'feComponentTransfer'
    | 'feComposite'
    | 'feConvolveMatrix'
    | 'feDiffuseLighting'
    | 'feDisplacementMap'
    | 'feDistantLight'
    | 'feDropShadow'
    | 'feFlood'
    | 'feFuncA'
    | 'feFuncB'
    | 'feFuncG'
    | 'feFuncR'
    | 'feGaussianBlur'
    | 'feImage'
    | 'feMerge'
    | 'feMergeNode'
    | 'feMorphology'
    | 'feOffset'
    | 'fePointLight'
    | 'feSpecularLighting'
    | 'feSpotLight'
    | 'feTile'
    | 'feTurbulence'
    | 'filter'
    | 'foreignObject'
    | 'g'
    | 'image'
    | 'line'
    | 'linearGradient'
    | 'marker'
    | 'mask'
    | 'metadata'
    | 'mpath'
    | 'path'
    | 'pattern'
    | 'polygon'
    | 'polyline'
    | 'radialGradient'
    | 'rect'
    | 'set'
    | 'stop'
    | 'switch'
    | 'text'
    | 'textPath'
    | 'tspan'
    | 'use'
    | 'view';
}

useRender.RenderPropHide

type useRenderRenderProp<TState = Record<string, unknown>> =
  | ReactElement
  | ((props: React.HTMLAttributes<any>, state: TState) => ReactElement)

useRender.ReturnValueHide

type useRenderReturnValue = ReactElement | null

HTMLPropsHide

type HTMLProps<T = any> = React.HTMLAttributes<T> & { ref?: React.Ref<T> }

UseRenderComponentPropsHide

type UseRenderComponentProps<
  ElementType extends React.ElementType,
  State = {},
  RenderFunctionProps = HTMLProps,
> = React.ComponentPropsWithRef<ElementType> & {
  render?: ReactElement | ((props: RenderFunctionProps, state: State) => ReactElement);
}

UseRenderElementPropsHide

type UseRenderElementProps =
  | (React.PropsWithoutRef<Props> & React.RefAttributes<R | any>)
  | Props
  | React.ComponentProps<React.ElementType>

UseRenderParametersHide

type UseRenderParameters<
  State,
  RenderedElementType extends Element,
  Enabled extends boolean | undefined,
> = {
  /** The React element or a function that returns one to override the default element. */
  render?: UseRenderRenderProp<State>;
  /** The ref to apply to the rendered element. */
  ref?: React.Ref<RenderedElementType> | React.Ref<RenderedElementType>[];
  /**
   * The state of the component, passed as the second argument to the `render` callback.
   * State properties are automatically converted to data-* attributes.
   */
  state?: State;
  /**
   * Custom mapping for converting state properties to data-* attributes.
   * @example { isActive: (value) => (value ? { 'data-is-active': '' } : null) }
   */
  stateAttributesMapping?: StateAttributesMapping<State>;
  /**
   * Props to be spread on the rendered element.
   * They are merged with the internal props of the component, so that event handlers
   * are merged, `className` strings and `style` properties are joined, while other external props overwrite the
   * internal ones.
   */
  props?: Record<string, unknown>;
  /**
   * If `false`, the hook will skip most of its internal logic and return `null`.
   * This is useful for rendering a component conditionally.
   * @default true
   */
  enabled?: boolean | undefined;
  /**
   * The default tag name to use for the rendered element when `render` is not provided.
   * @default 'div'
   */
  defaultTagName?:
    | 'symbol'
    | 'object'
    | 'a'
    | 'abbr'
    | 'address'
    | 'area'
    | 'article'
    | 'aside'
    | 'audio'
    | 'b'
    | 'base'
    | 'bdi'
    | 'bdo'
    | 'big'
    | 'blockquote'
    | 'body'
    | 'br'
    | 'button'
    | 'canvas'
    | 'caption'
    | 'center'
    | 'cite'
    | 'code'
    | 'col'
    | 'colgroup'
    | 'data'
    | 'datalist'
    | 'dd'
    | 'del'
    | 'details'
    | 'dfn'
    | 'dialog'
    | 'div'
    | 'dl'
    | 'dt'
    | 'em'
    | 'embed'
    | 'fieldset'
    | 'figcaption'
    | 'figure'
    | 'footer'
    | 'form'
    | 'h1'
    | 'h2'
    | 'h3'
    | 'h4'
    | 'h5'
    | 'h6'
    | 'head'
    | 'header'
    | 'hgroup'
    | 'hr'
    | 'html'
    | 'i'
    | 'iframe'
    | 'img'
    | 'input'
    | 'ins'
    | 'kbd'
    | 'keygen'
    | 'label'
    | 'legend'
    | 'li'
    | 'link'
    | 'main'
    | 'map'
    | 'mark'
    | 'menu'
    | 'menuitem'
    | 'meta'
    | 'meter'
    | 'nav'
    | 'noindex'
    | 'noscript'
    | 'ol'
    | 'optgroup'
    | 'option'
    | 'output'
    | 'p'
    | 'param'
    | 'picture'
    | 'pre'
    | 'progress'
    | 'q'
    | 'rp'
    | 'rt'
    | 'ruby'
    | 's'
    | 'samp'
    | 'search'
    | 'slot'
    | 'script'
    | 'section'
    | 'select'
    | 'small'
    | 'source'
    | 'span'
    | 'strong'
    | 'style'
    | 'sub'
    | 'summary'
    | 'sup'
    | 'table'
    | 'template'
    | 'tbody'
    | 'td'
    | 'textarea'
    | 'tfoot'
    | 'th'
    | 'thead'
    | 'time'
    | 'title'
    | 'tr'
    | 'track'
    | 'u'
    | 'ul'
    | 'var'
    | 'video'
    | 'wbr'
    | 'webview'
    | 'svg'
    | 'animate'
    | 'animateMotion'
    | 'animateTransform'
    | 'circle'
    | 'clipPath'
    | 'defs'
    | 'desc'
    | 'ellipse'
    | 'feBlend'
    | 'feColorMatrix'
    | 'feComponentTransfer'
    | 'feComposite'
    | 'feConvolveMatrix'
    | 'feDiffuseLighting'
    | 'feDisplacementMap'
    | 'feDistantLight'
    | 'feDropShadow'
    | 'feFlood'
    | 'feFuncA'
    | 'feFuncB'
    | 'feFuncG'
    | 'feFuncR'
    | 'feGaussianBlur'
    | 'feImage'
    | 'feMerge'
    | 'feMergeNode'
    | 'feMorphology'
    | 'feOffset'
    | 'fePointLight'
    | 'feSpecularLighting'
    | 'feSpotLight'
    | 'feTile'
    | 'feTurbulence'
    | 'filter'
    | 'foreignObject'
    | 'g'
    | 'image'
    | 'line'
    | 'linearGradient'
    | 'marker'
    | 'mask'
    | 'metadata'
    | 'mpath'
    | 'path'
    | 'pattern'
    | 'polygon'
    | 'polyline'
    | 'radialGradient'
    | 'rect'
    | 'set'
    | 'stop'
    | 'switch'
    | 'text'
    | 'textPath'
    | 'tspan'
    | 'use'
    | 'view';
}

UseRenderRenderPropHide

type UseRenderRenderProp<State = Record<string, unknown>> =
  | ReactElement
  | ((props: React.HTMLAttributes<any>, state: State) => ReactElement)

UseRenderReturnValueHide

type UseRenderReturnValue = ReactElement | null

UseRenderStateHide

type UseRenderState = {}