React.js functional components

React.js functional components are JavaScript functions that return React elements. They are an alternative to class-based components and can be used to define the structure and behavior of a component. Some commonly used functional components in React.js are:

1. React.Fragment: This component allows you to group a list of children without adding extra nodes to the DOM.

2. React.Suspense: This component allows you to declaratively "wait" for some code to load before rendering a component.

3. React.lazy: This component allows you to load a component lazily. It helps to reduce the size of the initial bundle by loading code only as it is needed.

4. React.Memo: This component allows you to memoize a component so that it only re-renders if its props have changed.

5. React.StrictMode: This component helps you to find potential problems in your code.

6. React.Portal: This component allows you to render children into a different part of the DOM, outside of the component hierarchy.

Please note that these are only a subset of the functional components available in React.js, and new functional components may be added in future releases.