Rendering React elements
The ReactDOM.render() method takes three parameters: ReactElement, a regular DOMElement container, and a callback function:
ReactDOM.render(ReactElement, DOMElement, callback);
A ReactElement type is a root element in the tree of ReactNode that you've created. A regular DOMElement parameter is a container DOM node for that tree. The callback parameter is a function executed after the tree is rendered or updated. It's important to note that if this ReactElement type was previously rendered to a parent DOMElement container, then ReactDOM.render() will perform an update on the already rendered DOM tree and only mutate the DOM, as it is necessary to reflect the latest version of the ReactElement type. This is why a virtual DOM requires fewer DOM mutations.
So far, we've assumed that we're always creating our virtual DOM in a web browser. This is understandable because, after all, React is a user interface library, and all user interfaces are rendered...
