Render Props - Share behavior between components by passing a function that returns JSX

Q: Should you export the render prop argument type for consumers?

Yes. Exporting the type (e.g., DisclosureRenderProps) lets consumers type their render functions externally. This improves autocomplete and catches type errors when the render function is defined in a separate file.

Recipe

// A headless component that manages mouse position
function MouseTracker({ render }: {
  render: (position: { x: number; y: number }) => React.ReactNode;
}) {
  const [position, setPosition] = useState({ x: 0, y: 0 });
 
  const handleMouseMove = (e: React.MouseEvent) => {
    setPosition({ x: e.clientX, y: e.clientY });
  };
 
  return <div onMouseMove={handleMouseMove}>{render(position)}</div>;
}
 
// Usage
<MouseTracker
  render={({ x, y }) => <p>Mouse is at ({x}, {y})</p>}
/>

When to reach for this: When a component encapsulates reusable behavior or state logic and the consumer needs to control what gets rendered. Also useful for headless UI components.

Working Example

import { useState, useRef, useEffect, type ReactNode } from "react";
 
// Headless disclosure component using render prop
interface DisclosureRenderProps {
  isOpen: boolean;
  toggle: () => void;
  open: () => void;
  close: () => void;
  triggerProps: {
    onClick: () => void;
    "aria-expanded": boolean;
    "aria-controls": string;
  };
  contentProps: {
    id: string;
    role: "region";
    hidden: boolean;
  };
}
 
function Disclosure({
  id,
  defaultOpen = false,
  children,
}: {
  id: string;
  defaultOpen?: boolean;
  children: (props: DisclosureRenderProps) => ReactNode;
}) {
  const [isOpen, setIsOpen] = useState(defaultOpen);
  const contentId = `${id}-content`;
 
  const api: DisclosureRenderProps = {
    isOpen,
    toggle: () => setIsOpen((prev) => !prev),
    open: () => setIsOpen(true),
    close: () => setIsOpen(false),
    triggerProps: {
      onClick: () => setIsOpen((prev) => !prev),
      "aria-expanded": isOpen,
      "aria-controls": contentId,
    },
    contentProps: {
      id: contentId,
      role: "region",
      hidden: !isOpen,
    },
  };
 
  return <>{children(api)}</>;
}
 
// Usage - full control over rendering
function FAQ({ items }: { items: { q: string; a: string }[] }) {
  return (
    <div className="space-y-2">
      {items.map((item, i) => (
        <Disclosure key={i} id={`faq-${i}`}>
          {({ triggerProps, contentProps, isOpen }) => (
            <div className="border rounded-lg">
              <button
                {...triggerProps}
                className="w-full text-left p-4 font-medium flex justify-between"
              >
                {item.q}
                <span>{isOpen ? "−" : "+"}</span>
              </button>
              <div {...contentProps} className="px-4 pb-4 text-gray-600">
                {item.a}
              </div>
            </div>
          )}
        </Disclosure>
      ))}
    </div>
  );
}

What this demonstrates:

Function-as-children pattern (the most common render prop variant)
Headless component - manages state and ARIA but renders nothing on its own
Consumer gets full control over DOM structure and styling
Accessibility props are provided by the headless component

Deep Dive

How It Works

A render prop is any prop whose value is a function that returns ReactNode.
The component calls this function during render, passing internal state or computed values as arguments.
The children variant (children: (props) => ReactNode) is the most common form, sometimes called "function-as-children."
The pattern separates behavior (state management, event handling, accessibility) from presentation (DOM, styles).
Headless UI libraries (Headless UI, Radix primitives, Downshift) are built on this concept.

Parameters & Return Values

Parameter	Type	Purpose
`render` or `children`	`(state: T) => ReactNode`	Function the consumer provides to control rendering
Internal state	Varies	Passed as argument to the render function
Event handlers	`() => void` etc.	Provided to the consumer for binding to their own elements
ARIA props	Spread objects	Pre-built accessibility attributes for consumer elements

Variations

Named render prop - useful when you need multiple render slots:

function DataTable<T>({
  data,
  renderHeader,
  renderRow,
  renderEmpty,
}: {
  data: T[];
  renderHeader: () => ReactNode;
  renderRow: (item: T, index: number) => ReactNode;
  renderEmpty: () => ReactNode;
}) {
  if (data.length === 0) return <>{renderEmpty()}</>;
  return (
    <table>
      <thead>{renderHeader()}</thead>
      <tbody>{data.map((item, i) => renderRow(item, i))}</tbody>
    </table>
  );
}

Prop collection pattern - group related props into spreadable objects:

// Instead of individual props:
// onClick={toggle} aria-expanded={isOpen} aria-controls={id}
 
// Provide a collection:
// {...triggerProps}

TypeScript Notes

Always type the render function argument explicitly so consumers get autocomplete.
Use generics for render props that work with varying data types: children: (item: T) => ReactNode.
Export the render prop argument type so consumers can type their render functions externally if needed.

Gotchas

New function on every render - Inline render props create a new function each render, which can interfere with React.memo. Fix: Extract the render function to a stable reference with useCallback if the parent is memoized.
Wrapper hell - Nesting multiple render prop components creates deep indentation. Fix: Extract custom hooks for the behavior instead. Most render prop patterns can be converted to hooks.
Returning fragments without keys - When render props return lists, each item needs a key. Fix: Ensure the consumer returns keyed elements when rendering lists.
Breaking rules of hooks inside render props - You cannot call hooks inside the render function passed to a render prop. Fix: If hooks are needed, extract a separate component and pass data as props.

Alternatives

Approach	Trade-off
Render props	Full rendering control; can lead to nesting
Custom hooks	Cleaner API; cannot encapsulate JSX structure
Composition (slots)	Simpler; slot content cannot access internal state
Higher-order components	Adds behavior transparently; harder to type correctly
Compound components	Multiple related elements share state implicitly

FAQs

What is the difference between a render prop and function-as-children?

A render prop is any prop whose value is a function that returns ReactNode.
Function-as-children is a specific variant where children is the render function: children: (props) => ReactNode.
Function-as-children is the most common form and avoids the extra prop name.

What is a headless component?

A headless component manages state, event handling, and accessibility but renders no DOM of its own.
The consumer controls all rendering through a render prop.
Libraries like Headless UI, Radix, and Downshift are built on this concept.

How does the prop collection pattern simplify render props?

// Instead of passing individual props:
// onClick={toggle} aria-expanded={isOpen} aria-controls={id}
 
// Provide a spreadable object:
// {...triggerProps}

Group related props (event handlers, ARIA attributes) into a single object.
Consumers spread the object onto their element, reducing boilerplate and preventing missed attributes.

When should you use multiple named render props instead of a single children render prop?

<DataTable
  data={rows}
  renderHeader={() => <tr><th>Name</th></tr>}
  renderRow={(item) => <tr><td>{item.name}</td></tr>}
  renderEmpty={() => <p>No data</p>}
/>

Use multiple named render props when the component has distinct rendering slots (header, row, empty state).
A single children render prop works when there is only one rendering area.

Gotcha: Why can inline render props break `React.memo`?

Inline render functions create a new function reference on every render.
If the parent component is memoized, the new reference causes it to re-render regardless.
Fix: extract the render function and stabilize it with useCallback if the parent is memoized.

Gotcha: Can you call hooks inside a render prop function?

No. Hooks cannot be called inside the render function passed to a render prop.
The function runs during the parent's render, not as its own component.
Fix: extract a separate component that receives the data as props and calls hooks inside that component.

How do you type a generic render prop in TypeScript?

interface ListProps<T> {
  items: T[];
  children: (item: T, index: number) => ReactNode;
}
 
function List<T>({ items, children }: ListProps<T>) {
  return <ul>{items.map((item, i) => <li key={i}>{children(item, i)}</li>)}</ul>;
}

Use a generic type parameter on both the component and the render function.
TypeScript infers T from the items array and enforces it in the render function argument.

Should you export the render prop argument type for consumers?

Yes. Exporting the type (e.g., DisclosureRenderProps) lets consumers type their render functions externally.
This improves autocomplete and catches type errors when the render function is defined in a separate file.

Why are render props less common in modern React, and what replaced them?

Custom hooks can encapsulate the same reusable behavior without nesting.
Hooks provide a cleaner API and avoid the deep indentation ("wrapper hell") of nested render props.
Render props are still useful when you need to encapsulate JSX structure, not just logic.

How do render props handle accessibility compared to composition?

Render props can provide pre-built ARIA attribute objects (like triggerProps and contentProps) for the consumer to spread.
The headless component owns the accessibility logic while the consumer owns the DOM structure.
This is how libraries like Downshift and Headless UI deliver accessible widgets without dictating markup.

How do you avoid wrapper hell with multiple render prop components?

Extract each render prop component's behavior into a custom hook.
Use the hooks together in a single component instead of nesting render prop wrappers.
Most render prop patterns have a direct hook equivalent.

Composition - Simpler alternative when slots don't need internal state
Higher-Order Components - Alternative pattern for behavior reuse
Compound Components - Multi-part API that shares state via context

Recipe

// A headless component that manages mouse position
function MouseTracker({ render }: {
  render: (position: { x: number; y: number }) => React.ReactNode;
}) {
  const [position, setPosition] = useState({ x: 0, y: 0 });
 
  const handleMouseMove = (e: React.MouseEvent) => {
    setPosition({ x: e.clientX, y: e.clientY });
  };
 
  return <div onMouseMove={handleMouseMove}>{render(position)}</div>;
}
 
// Usage
<MouseTracker
  render={({ x, y }) => <p>Mouse is at ({x}, {y})</p>}
/>

When to reach for this: When a component encapsulates reusable behavior or state logic and the consumer needs to control what gets rendered. Also useful for headless UI components.

Working Example

import { useState, useRef, useEffect, type ReactNode } from "react";
 
// Headless disclosure component using render prop
interface DisclosureRenderProps {
  isOpen: boolean;
  toggle: () => void;
  open: () => void;
  close: () => void;
  triggerProps: {
    onClick: () => void;
    "aria-expanded": boolean;
    "aria-controls": string;
  };
  contentProps: {
    id: string;
    role: "region";
    hidden: boolean;
  };
}
 
function Disclosure({
  id,
  defaultOpen = false,
  children,
}: {
  id: string;
  defaultOpen?: boolean;
  children: (props: DisclosureRenderProps) => ReactNode;
}) {
  const [isOpen, setIsOpen] = useState(defaultOpen);
  const contentId = `${id}-content`;
 
  const api: DisclosureRenderProps = {
    isOpen,
    toggle: () => setIsOpen((prev) => !prev),
    open: () => setIsOpen(true),
    close: () => setIsOpen(false),
    triggerProps: {
      onClick: () => setIsOpen((prev) => !prev),
      "aria-expanded": isOpen,
      "aria-controls": contentId,
    },
    contentProps: {
      id: contentId,
      role: "region",
      hidden: !isOpen,
    },
  };
 
  return <>{children(api)}</>;
}
 
// Usage - full control over rendering
function FAQ({ items }: { items: { q: string; a: string }[] }) {
  return (
    <div className="space-y-2">
      {items.map((item, i) => (
        <Disclosure key={i} id={`faq-${i}`}>
          {({ triggerProps, contentProps, isOpen }) => (
            <div className="border rounded-lg">
              <button
                {...triggerProps}
                className="w-full text-left p-4 font-medium flex justify-between"
              >
                {item.q}
                <span>{isOpen ? "−" : "+"}</span>
              </button>
              <div {...contentProps} className="px-4 pb-4 text-gray-600">
                {item.a}
              </div>
            </div>
          )}
        </Disclosure>
      ))}
    </div>
  );
}

What this demonstrates:

Function-as-children pattern (the most common render prop variant)
Headless component - manages state and ARIA but renders nothing on its own
Consumer gets full control over DOM structure and styling
Accessibility props are provided by the headless component

Deep Dive

How It Works

A render prop is any prop whose value is a function that returns ReactNode.
The component calls this function during render, passing internal state or computed values as arguments.
The children variant (children: (props) => ReactNode) is the most common form, sometimes called "function-as-children."
The pattern separates behavior (state management, event handling, accessibility) from presentation (DOM, styles).
Headless UI libraries (Headless UI, Radix primitives, Downshift) are built on this concept.

Parameters & Return Values

Parameter	Type	Purpose
`render` or `children`	`(state: T) => ReactNode`	Function the consumer provides to control rendering
Internal state	Varies	Passed as argument to the render function
Event handlers	`() => void` etc.	Provided to the consumer for binding to their own elements
ARIA props	Spread objects	Pre-built accessibility attributes for consumer elements

Variations

Named render prop - useful when you need multiple render slots:

function DataTable<T>({
  data,
  renderHeader,
  renderRow,
  renderEmpty,
}: {
  data: T[];
  renderHeader: () => ReactNode;
  renderRow: (item: T, index: number) => ReactNode;
  renderEmpty: () => ReactNode;
}) {
  if (data.length === 0) return <>{renderEmpty()}</>;
  return (
    <table>
      <thead>{renderHeader()}</thead>
      <tbody>{data.map((item, i) => renderRow(item, i))}</tbody>
    </table>
  );
}

Prop collection pattern - group related props into spreadable objects:

// Instead of individual props:
// onClick={toggle} aria-expanded={isOpen} aria-controls={id}
 
// Provide a collection:
// {...triggerProps}

TypeScript Notes

Always type the render function argument explicitly so consumers get autocomplete.
Use generics for render props that work with varying data types: children: (item: T) => ReactNode.
Export the render prop argument type so consumers can type their render functions externally if needed.

Gotchas

New function on every render - Inline render props create a new function each render, which can interfere with React.memo. Fix: Extract the render function to a stable reference with useCallback if the parent is memoized.
Wrapper hell - Nesting multiple render prop components creates deep indentation. Fix: Extract custom hooks for the behavior instead. Most render prop patterns can be converted to hooks.
Returning fragments without keys - When render props return lists, each item needs a key. Fix: Ensure the consumer returns keyed elements when rendering lists.
Breaking rules of hooks inside render props - You cannot call hooks inside the render function passed to a render prop. Fix: If hooks are needed, extract a separate component and pass data as props.

Alternatives

Approach	Trade-off
Render props	Full rendering control; can lead to nesting
Custom hooks	Cleaner API; cannot encapsulate JSX structure
Composition (slots)	Simpler; slot content cannot access internal state
Higher-order components	Adds behavior transparently; harder to type correctly
Compound components	Multiple related elements share state implicitly

FAQs

What is the difference between a render prop and function-as-children?

A render prop is any prop whose value is a function that returns ReactNode.
Function-as-children is a specific variant where children is the render function: children: (props) => ReactNode.
Function-as-children is the most common form and avoids the extra prop name.

What is a headless component?

A headless component manages state, event handling, and accessibility but renders no DOM of its own.
The consumer controls all rendering through a render prop.
Libraries like Headless UI, Radix, and Downshift are built on this concept.

How does the prop collection pattern simplify render props?

// Instead of passing individual props:
// onClick={toggle} aria-expanded={isOpen} aria-controls={id}
 
// Provide a spreadable object:
// {...triggerProps}

Group related props (event handlers, ARIA attributes) into a single object.
Consumers spread the object onto their element, reducing boilerplate and preventing missed attributes.

When should you use multiple named render props instead of a single children render prop?

<DataTable
  data={rows}
  renderHeader={() => <tr><th>Name</th></tr>}
  renderRow={(item) => <tr><td>{item.name}</td></tr>}
  renderEmpty={() => <p>No data</p>}
/>

Use multiple named render props when the component has distinct rendering slots (header, row, empty state).
A single children render prop works when there is only one rendering area.

Gotcha: Why can inline render props break `React.memo`?

Inline render functions create a new function reference on every render.
If the parent component is memoized, the new reference causes it to re-render regardless.
Fix: extract the render function and stabilize it with useCallback if the parent is memoized.

Gotcha: Can you call hooks inside a render prop function?

No. Hooks cannot be called inside the render function passed to a render prop.
The function runs during the parent's render, not as its own component.
Fix: extract a separate component that receives the data as props and calls hooks inside that component.

How do you type a generic render prop in TypeScript?

interface ListProps<T> {
  items: T[];
  children: (item: T, index: number) => ReactNode;
}
 
function List<T>({ items, children }: ListProps<T>) {
  return <ul>{items.map((item, i) => <li key={i}>{children(item, i)}</li>)}</ul>;
}

Use a generic type parameter on both the component and the render function.
TypeScript infers T from the items array and enforces it in the render function argument.

Should you export the render prop argument type for consumers?

Yes. Exporting the type (e.g., DisclosureRenderProps) lets consumers type their render functions externally.
This improves autocomplete and catches type errors when the render function is defined in a separate file.

Why are render props less common in modern React, and what replaced them?

Custom hooks can encapsulate the same reusable behavior without nesting.
Hooks provide a cleaner API and avoid the deep indentation ("wrapper hell") of nested render props.
Render props are still useful when you need to encapsulate JSX structure, not just logic.

How do render props handle accessibility compared to composition?

Render props can provide pre-built ARIA attribute objects (like triggerProps and contentProps) for the consumer to spread.
The headless component owns the accessibility logic while the consumer owns the DOM structure.
This is how libraries like Downshift and Headless UI deliver accessible widgets without dictating markup.

How do you avoid wrapper hell with multiple render prop components?

Extract each render prop component's behavior into a custom hook.
Use the hooks together in a single component instead of nesting render prop wrappers.
Most render prop patterns have a direct hook equivalent.

Composition - Simpler alternative when slots don't need internal state
Higher-Order Components - Alternative pattern for behavior reuse
Compound Components - Multi-part API that shares state via context

Render Props - Share behavior between components by passing a function that returns JSX

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Render Props - Share behavior between components by passing a function that returns JSX