React usePortal Hook

Introduction

In this lab, we will be exploring the use of the usePortal hook in React. The purpose of this hook is to create a portal that allows rendering of children outside the parent component. We will learn how to use the useState(), useCallback(), and useEffect() hooks to create and manage a portal, as well as how to use ReactDOM.createPortal() and ReactDOM.unmountComponentAtNode() to render and remove the portal.

React usePortal Hook

index.html and script.js have already been provided in the VM. In general, you only need to add code to script.js and style.css.

To create a portal that renders children outside the parent component, follow these steps:

1. Use the useState() hook to create a state variable that holds the render() and remove() functions for the portal.
2. Use ReactDOM.createPortal() and ReactDOM.unmountComponentAtNode() to create a portal and a function to remove it. Use the useCallback() hook to wrap and memoize these functions as createPortal().
3. Use the useEffect() hook to call createPortal() and update the state variable any time el's value changes.
4. Finally, return the render() function of the state variable.

Here's an example implementation:

const usePortal = (el) => {
  const [portal, setPortal] = React.useState({
    render: () => null,
    remove: () => null
  });

  const createPortal = React.useCallback((el) => {
    const Portal = ({ children }) => ReactDOM.createPortal(children, el);
    const remove = () => ReactDOM.unmountComponentAtNode(el);
    return { render: Portal, remove };
  }, []);

  React.useEffect(() => {
    if (el) portal.remove();
    const newPortal = createPortal(el);
    setPortal(newPortal);
    return () => newPortal.remove(el);
  }, [el]);

  return portal.render;
};

To use this hook, create a component that calls usePortal() with the desired DOM element as an argument. This component can then use the returned render() function to render content in the portal:

const App = () => {
  const Portal = usePortal(document.querySelector("title"));

  return (
    <p>
      Hello world!
      <Portal>Portalized Title</Portal>
    </p>
  );
};

ReactDOM.createRoot(document.getElementById("root")).render(<App />);

Please click on 'Go Live' in the bottom right corner to run the web service on port 8080. Then, you can refresh the Web 8080 Tab to preview the web page.

Summary

Congratulations! You have completed the React usePortal Hook lab. You can practice more labs in LabEx to improve your skills.