Render Elements Outside the Current React Tree using Portals in React 16
By default the React Component Tree directly maps to the DOM Tree. In some cases when you have UI elements like overlays or loading bars this can be limiting. React 16 therefor ships with the new portal feature allowing you to attach parts of the Component tree inside a different root element.
This lesson explores the new functionality by building an
<Overlay/> component that renders out its children and creates a closeable overlay outside its DOM node.