Building Components

# Building Components

## When to use this skill

Use when the user is:

- Building new UI components (primitives, components, blocks, templates)
- Implementing accessibility features (ARIA, keyboard navigation, focus management)
- Creating composable component APIs (slots, render props, controlled/uncontrolled state)
- Setting up design tokens and theming systems
- Publishing components to npm or a registry
- Writing component documentation
- Implementing polymorphism or as-child patterns
- Working with data attributes for styling/state

## References

- [definitions.mdx](./references/definitions.mdx) - Artifact taxonomy (primitives, components, blocks, templates)
- [principles.mdx](./references/principles.mdx) - Core principles for component design
- [accessibility.mdx](./references/accessibility.mdx) - ARIA, keyboard navigation, WCAG compliance
- [composition.mdx](./references/composition.mdx) - Composable component patterns
- [as-child.mdx](./references/as-child.mdx) - The as-child pattern for element polymorphism
- [polymorphism.mdx](./references/polymorphism.mdx) - Polymorphic component patterns
- [types.mdx](./references/types.mdx) - TypeScript typing patterns for components
- [state.mdx](./references/state.mdx) - Controlled vs uncontrolled state management
- [data-attributes.mdx](./references/data-attributes.mdx) - Using data attributes for styling and state
- [design-tokens.mdx](./references/design-tokens.mdx) - Design token systems and theming
- [styling.mdx](./references/styling.mdx) - Component styling approaches
- [registry.mdx](./references/registry.mdx) - shadcn-style registry distribution
- [npm.mdx](./references/npm.mdx) - Publishing components to npm
- [marketplaces.mdx](./references/marketplaces.mdx) - Component marketplace distribution
- [docs.mdx](./references/docs.mdx) - Writing component documentation


---
title: Polymorphism
description: How to use the `as` prop to change the rendered HTML element while preserving component functionality.
type: reference
summary: The as prop pattern for polymorphic components, compared with Radix UI's Slot-based asChild approach with TypeScript best practices.
prerequisites:
  - /composition
  - /types
related:
  - /as-child
  - /accessibility
---

The `as` prop is a fundamental pattern in modern React component libraries that allows you to change the underlying HTML element or component that gets rendered.

Popularized by libraries like [Styled Components](https://styled-components.com/), [Emotion](https://emotion.sh/), and [Chakra UI](https://chakra-ui.com/), this pattern provides flexibility in choosing semantic HTML while maintaining component styling and behavior.

The `as` prop enables polymorphic components - components that can render as different element types while preserving their core functionality:

```tsx
<Button as="a" href="/home">
  Go Home
</Button>

<Button as="button" type="submit">
  Submit Form
</Button>

<Button as="div" role="button" tabIndex={0}>
  Custom Element
</Button>
```

## Understanding `as`

The `as` prop allows you to override the default element type of a component. Instead of being locked into a specific HTML element, you can adapt the component to render as any valid HTML tag or even another React component.

For example:

```tsx
// Default renders as a div
<Box>Content</Box>

// Renders as a section
<Box as="section">Content</Box>

// Renders as a nav
<Box as="nav">Content</Box>
```

This renders different HTML elements:

```html
<!-- Default -->
<div>Content</div>

<!-- With as="section" -->
<section>Content</section>

<!-- With as="nav" -->
<nav>Content</nav>
```

## Implementation Methods

There are two main approaches to implementing pol