Portals

There are a variety of UI patterns that require a component render some part of its UI that appears outside of the component's normal DOM hierarchy. For example, a modal dialog might need to render its contents at the root of the document, or a tooltip might need to render its contents at the end of the body element. Typically this is for the purpose of layering or positioning content above other content.

You could imperatively add a useEffect that creates a DOM node yourself, appends it to the document, and then removes it when the component unmounts. However, this is a common enough pattern that React provides a built-in way to do this with the ReactDOM.createPortal method.

import { createPortal } from 'react-dom'

function Modal({
	title,
	content,
	handleClose,
}: {
	title: string
	content: string
	handleClose: () => void
}) {
	return createPortal(
		<div className="modal">
			<h1>{title}</h1>
			<p>{content}</p>
		</div>,
		document.body,
	)
}

function App() {
	const [showModal, setShowModal] = React.useState(false)

	return (
		<div>
			<button onClick={() => setShowModal(true)}>Show Modal</button>
			{showModal && (
				<Modal
					title="My Modal"
					content="This is the content of the modal"
					handleClose={() => setShowModal(false)}
				/>
			)}
		</div>
	)
}

The first argument is the UI you want rendered (which has access to props, state, whatever) and the second argument is the DOM node you want to render it to. In this case, we're rendering the modal to the body element.

📜 Learn more from the createPortal docs