What is the React portals API (ReactDOM.createPortal) used for and when is it necessary?

Question

React Developer — Hard

What is the React portals API (ReactDOM.createPortal) used for and when is it necessary?

Accepted Answer

The React portals API (ReactDOM.createPortal) is used to render children into a DOM node outside the parent component's hierarchy, necessary for elements like modals and tooltips. This allows these components to visually escape certain constraints like overflow:hidden or z-index stacking contexts.