Dynamic Tag Name Props in React (with TypeScript)

In React, you'll sometimes want to allow users to pass in a dynamic tag name as a prop to a component. While this is a somewhat rare pattern, you may still come across it in the wild. For example, you may have seen it if you've ever worked with the react-intl library for internationalized strings, where the <FormattedMessage> component accepts an optional tagName prop:

<FormattedMessage id="common.close" tagName="p" />

To keep this demo simple, let's say we want to create a reusable CenteredContainer component to encapsulate some CSS or other logic (I won't show any of that here):

import React, { FC } from 'react';

interface CenteredContainerProps {
  className?: string;
}

const CenteredContainer: FC<CenteredContainerProps> = (props) => <div {...props} />;

You could always render a <div> like we're doing here, but that's not a great idea. It pollutes your DOM with an extra decorative <div>, making it difficult to write semantic HTML markup. Plus, there's no reason why a centered container should always be a <div>. This may even be invalid HTML depending on where you intend to use the container.

Fortunately, we can take advantage of TypeScript's intellisense and pass a dynamic tag name as a prop to change the rendered tag:

import React, { FC } from 'react';

interface CenteredContainerProps extends React.HTMLAttributes<HTMLOrSVGElement> {
  tagName?: keyof JSX.IntrinsicElements;
  className?: string;
}

const CenteredContainer: FC<CenteredContainerProps> = ({ tagName, ...otherProps }) => {
  const Tag = tagName as keyof JSX.IntrinsicElements;
  return <Tag {...otherProps} />;
};

CenteredContainer.defaultProps = {
  tagName: 'div',
};

export default CenteredContainer;

There are two things worth noting here.

First, React expects element types to start with a capital letter. Lowercase element names are reserved for built-in tags like <div>, for example. But we want to follow the convention of using lowercase names for props. To get around this, we create a new, uppercase variable Tag that gets a copy of tagName:

const Tag = tagName as keyof JSX.IntrinsicElements;

Second, you may be wondering why we're using a type assertion here (as well as in the interface):

as keyof JSX.IntrinsicElements

That addresses the following error, letting TypeScript know that our Tag variable does in fact resolve to one of the built-in (intrinsic) callable element types, like <div>, <button>, and so on:

"JSX element type 'Tag' does not have any construct or call signatures"

Additionally, notice that our CenteredContainer component renders a <div> by default:

CenteredContainer.defaultProps = {
  tagName: 'div',
};

But you can override this by passing in a custom tagName:

import CenteredContainer from 'components/CenteredContainer';
import React, { FC } from 'react';

const MyComponent: FC = ({ children }) => {
  return <CenteredContainer tagName="nav">{children}</CenteredContainer>
};

Since we've specified that tagName is keyof JSX.IntrinsicElements, we'll get auto-complete intellisense whenever we try to set this prop:

In some cases, you may want to instead use render props, but they're not always needed—sometimes, all you really want is to be able to specify a tag name as a string. You typically only need to use render props if the element being rendered depends on some state. Here, we're just telling the component what to render by passing in a plain string. The syntax is shorter and easier to read.

And that's all there is to it! I hope you found this mini-tutorial helpful.

Attributions

The photo used in this post's social media preview was taken by Angèle Kamp (Unsplash).