A great use case for portals is for use with things like React modals. Anything that uses a stack context can obscure the css position for something like a modal.
The tl;dr is to make a React component a descendent of a HTML element other than id="root"
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import React from 'react'; import ReactDOM from 'react-dom'; const Modal = (props) => { return ReactDOM.createPortal( <div className="modal"> <div className="modal-body" /> </div>, document.querySelector('#modal') ); };